A crypto address is the string of letters and numbers you give someone when you want them to send you cryptocurrency. It is derived from your wallet public key, but shortened into a more manageable form. Different networks have different address formats, so a Bitcoin address looks different from an Ethereum one.
An address is safe to share publicly. Anyone who has it can send funds to you or look up past activity on a block explorer, but they cannot remove anything, since that still requires your private key. Many wallets let you generate multiple addresses, which can help keep different activities separate.
The main thing to get right is accuracy. Sending to a wrong or mistyped address can mean funds are lost for good, because most crypto transactions cannot be reversed. Always copy and paste, and double-check the first and last characters before confirming.