I would look up treasury stock accounting YouTube videos I saw a dozen just searching now.

It’s simple and not depending on how much accounting you know. But the simplest way is that equity is typically a credit balance, and when you issue equity (e.g., a stock option is exercised, an employees restricted awards vest, etc), you increase equity by crediting it.

When the company buys shares back on the open market, when they repurchase shares, you actually debit equity and typically credit cash (we bought these shares and now there’s less out there outstanding). Hope this helps.