Etherscan allows you to search and track the Ethereum blockchain for transactions, addresses, tokens, prices, and other activities taking place on the Ethereum blockchain.
To check your account details on Ethereum mainnet, please enter your public address into the search bar on etherscan.io, and you will see all of your account activity and transaction details.
After you enter your MetaMask public address, which is on Ethereum's mainnet, you will see the ETH balance in native value, today's fiat value and a separate total balance of all your custom ERC-20 tokens. You will also see all the up-to-date transactions in your wallet.
This balance should reflect in your MetaMask wallet. Please note: if you don't see your custom token, you need to add it manually following this article. If you're still having issues finding the tokens or your Ether balance isn't the same in your MetaMask wallet, see this article.
Note: if you deposit/send your token on a non-Ethereum Mainnet network you can check your balance and transactions on a different explorer. For example, you can preview your Binance Smart Chain activity on Binance Smart Chain Explorer. Learn more about sidechains and custom networks here.