If you've tried adding a new token to your wallet, one thing you will have noticed is the field asking for a Token Contract Address. This refers to the address location of the actual token contract that manages the logic for the tokens. It does not refer to the address that holds your own personal tokens!
The contract address is necessary for MetaMask to know exactly which token you're referring to. The address itself is the location of a smart contract which manages the balances of all token holders, amongst other things, such as the total supply and its basic features (name, decimals, etc.). For more information on token standards, see our tokens user guide.
To learn how to find a token's contract address, see our article here.