How to create a public key and private key using web3js?

I am learning to use web3js in this case to create an ethereum address and a private key to make a simple dapp.

Can anyone tell me to use this web3js? If you are pleased, I ask for help on how to use it :)

My achievement recently studied to see the balance of ethereum and token ERC20.

To further solidify this post, maybe there are also people who can share information about web3js as a reference for me and others who see this post :)