NAV tells you what one unit of a mutual fund is worth on a given day. If a fund holds assets worth ₹100 crore with ₹1 crore of liabilities and has 9.9 crore units, its NAV is ₹10.
When you invest, your money buys units at the current NAV; when you redeem, you sell at that day's NAV. A ₹6,000 investment at a NAV of ₹30 buys you 200 units.
A common myth is that a low NAV means a fund is cheap or better value. It does not — NAV simply reflects the fund's history and unit count. What matters for returns is the percentage change in NAV, not its absolute number.