blockchain – how to generate bitcoins with the help of seeds?

Hi, I'm new to Bitcoin All I want to know, is how to generate an address using the mnemonic seed?

let testnet = Bitcoin.networks.testnet;
let keypair = Bitcoin.ECPair.makeRandom ({network: testnet});
let address = keypair.getAddress ();
let privateKey = keypair.toWIF ();
res.json ("Public address" + address + "" + private key)