To use BSC with MetaMask, you must first add BSC to MetaMask as a network.
Step 1: Click on the network dropdown from the MetaMask plugin
Step 2: Select “Custom” and enter the following details
Network Name: Binance Smart Chain
New RPC URL: https://bsc-dataseed.binance.org
Chain ID: 56
Block Explorer URL: https://bscscan.com
Step 3: Click Save
Step 4: Select the network dropdown again and click “Binance Smart Chain.”
Your MetaMask is now configured to work with BSC. Any time you switch between Ethereum and BSC you must change the network on the dropdown.