STCG stands for Short-Term Capital Gains — the profit you earn from selling an asset that you held for a period shorter than the specified minimum holding period that would classify it as long-term. For listed equity shares and equity mutual funds, this means holding for 12 months or less; for most other assets, it's typically 24 or 36 months or less.
Short-term gains are generally taxed at a higher rate than long-term gains, which is intended to discourage excessive short-term trading and reward patient, long-term investing instead. For equity and equity mutual funds specifically, STCG is taxed at a flat rate, while STCG on other assets like debt funds or property is typically added to your total income and taxed at your regular income tax slab rate. Knowing this distinction can meaningfully influence when you choose to sell an investment.