Short answer
Market cap is the token's current price multiplied by its circulating supply. It's a rough size measure, not the amount of money you could actually take out.
If a token trades at $0.001 and there are 1 billion in circulation, its market cap is $1 million. That makes it easy to compare tokens with wildly different prices and supplies.
But market cap is a paper number. It assumes every token could be sold at the last price, which is never true. If the pool behind that $1 million token only holds $50,000, a large sell would crash the price long before anyone got near $1 million out.
That's why market cap should always be read alongside liquidity and volume.
See the checks for yourself
18+ only. Self-custodial: you keep your keys. 0.5% per trade, no minimum. Memecoins can go to zero.