Consider "Balancing" as from the verb infinitive "to Balance".
In bridge perhaps it's a "democratic idea": to hear from "the balance" - leftovers that haven't yet been heard from. "What of the balance? Nothing to say?"
Perhaps "Balancing" is a self-appointment by a player to speak on behalf of points not yet having 'made noise': 'the quiet points'.

1	Pass	1N	Pass
Pass	Pass

1	Pass	1N	Pass
Pass	?

What kind of a hand would bid here that wouldnt' already have bid? Many hand types have been denied by this player's original Pass.
A bid, or double, now suggests hands other than could not originally have done.
This player at first turn with 1 might have suggested 5 spades and 8+ points and 2 mght have suggested 6 spades with 5 to 10 points.
A 2 bid now would be a bit mysterious, wouldn't it?
Often balancing bids are mysterious to Balancer's Partner:
"Hmmmm...didn't originally have 5 spades with 8+ points.
Neither did partner have originally a weak 2 bid.
Didn't have a takeout double of 1.
Didn't double the 1N, whatever that would have been.
I'm totally confused. It's obviously an illegal bid for us." throwing down cards, exasperated.

1	Pass	1N	Pass
Pass	2!	Pass	huh?

There are all kinds of things that the 2 bid could mean.
It may well mean something different for each of a dozen partnerships and partners over time.
Could it really be a FOUR card spade suit with 8 points (QJT9 AJTx xxx xx)?
Even more confusin is that Balancer's partner might need to look at his/her own hand to determine what balancer is likely to hold.

If a possible 1N contract suggests points divided evenly, 20 for each side, and Balancer's partner holds 13 points and a balanced hand, then perhaps even 7 points has bid 2 on a 5 card suit that was too weak (needed 8 or more points) to bid 1 or a 6 card spade suit that failed a partnership suit quality test (didn't have two of the top 3 suit honours).

Balancing is a common practice of experienced partnerships.
Often inexperienced partners will raise a balancing 2 bid to 4 'remembering' an Audrey Grant inference that 13 points and 3 card major suit trump support, opposite the opening hand required to bid 2 over 1N, should raise to game.
I hate when that happens to me.
Doubled, down 2, in the red. Meanwhile, making 2, or even down one might have been an incredible score.
Instead it might have been: "I'm glad I passed with my 13 points and 3 spades, partner. Only 5 spades and 6 points, huh?"

If you're too cheap to buy a balancing book for each of yourself and partner, and finance your partner's paid sitting, reading and concurring with an authoritative text (many of us are), you might just sit and consider what kind of abominations might reasonably "balance" opposite YOUR 16 points that couldn't overcall or double.
You might reason: "The auction suggests that Partner probably has about the remaining 4 points of our half of the deck's 20."
" What ragged piece of refuse could that possibly be?"
Perhaps you're mischievous and consider: "Do I scare partner by faking grabbing the thick bunch of cards in the bidding box that would suggest a 4 bid?"
"That might be priceless. Do I stare at partner as I reach in or do I use my peripheral vision to catch the nervous tension from an innocent's perspective?"

On the other hand, I might be looking at 6 points and partner on balance might be assumed to have 14 points.
What is a 2 bid then? 14 points and couldn't bid even bid 1? Couldn't double? Partner can't have 5 spades then, right?
Any 5 spades with 14 points would have overcalled the 1 opening with 1. It's a 4 card suit.
Why wouldn't partner with 4 spades and 14 points double initially? Takeout doubles usually require 3+ cards in each outside suit.
Partner might have 4 spades, 4 hearts, 4 diamonds and 1 club.
In this case where partner has almost certainly exactly 4 spades, if I have only 2 spades, I should seriously consider other than passing because that would leave partner declaring in one of the opponent's 7 card suits at the two level, often unsuccessfully.

"What is your partner showing?" can be an annoying/perplexing/difficult question to ask of balancer's partner.
Since balancer's expected hand depends on what balancer's partner holds, answering that question entails:
1)a long winded series of theoretical replies covering what what a blinded balancer's partner might have agreed to and expect, or
2) revealing information to which neither opponents, nor balancer, are entitled to simply get it over with.
It would be an awkward balancing act of the "full disclosure" and/or "brevity" information-reporting-goals.

Novices should just forget balancing.
Experts are expected to apply it with at least other than expert partners.

Balancing can be thought of as done by a little old lady at a public auction that hdsn't even registered to bid.
She raises her hand on the 3rd, and last, call and an obliging auctioneer, recognizing her as a friend of his mother, accepts her bid reluctantly and later aside asks her "Why bid without a paddle and so late?"
"Well...I knew it was a good deal, I remembered that I had some foreign money in a hidden compartment in my purse and my husband always carries around $100 of mad money."

Balancing can be a study of abominable variances from bidding standards become attractive due to expected accruing returns.
No one really likes recycling, but most agree that ripping apart cardboard containers and carrying 3 different baskets up and down 3 flights of stairs is righteous.
Do it or the neighbours turn you in. You'll be sorry if you don't.
Balancing is maybe more like recycling then.
It's like buying functional yet shady 2nd hand goods. It may not be pretty, but it gets the job done. Maybe it's like duct tape. Enough with the 'likes' of balancing.

Mike Lawrence's Balancing includes one set of standard

"Why would I balance? You're a novice. You always have been and always will be."

"Almost never comes up."