IDCW, short for income distribution cum capital withdrawal, is the option in which a fund pays part of its NAV out to investors from time to time.
IDCW is the name SEBI gave in April 2021 to what used to be called the dividend option. The new name makes clear that a payout can include part of your own capital.
When a fund declares an IDCW, its NAV falls by the amount paid. If the NAV is ₹25 and the fund pays ₹1 a unit, the NAV becomes ₹24, before the day's market moves. Your total is unchanged; part of it has moved to your bank account.
The Growth option of the same plan pays nothing out and is taxed only when you redeem. A systematic withdrawal plan is another way to draw regular money from a fund, at an amount and date you choose.
Each fund page has its returns, risk, costs, managers and everything it holds.