ERC20 is a standard or a set of rules for Ethereum based tokens.
These tokens are smart contracts on the Ethereum network, each serving various purposes and uses. When sending an ERC20 token to another wallet, you will need to ensure you have ether in your wallet to cover the necessary transaction fees.
Fees are calculated according to the complexity of the transaction (gas), and paid in Ether. The amount of time for a block to be confirmed varies depending on the token and the amount of gas used.