Equity
Ownership value in an asset after all debts are subtracted. In markets, "equity" usually means stocks.
Equity = Assets − Liabilities
Equity has two related meanings in finance. At the company level, it is the residual value of assets after all liabilities are paid — what shareholders actually own. At the market level, "equities" is simply the asset class of stocks.
On a balance sheet: Equity = Assets − Liabilities. Positive equity means the company is solvent; negative equity means liabilities exceed assets (technically insolvent).
When traders say they "trade equities," they mean they trade stocks — the two words are interchangeable in most market contexts.