Hello, I opened a savings account at https://securelogin.synchronybank.com/myaccount/loginUserActionGetOnly and now they have sent me a w-9 form? why? Please be clear.

I opened the account because they give 1.01% interest rate but wasnt expecting a w-9 form. What does this mean? Do i have to pay money to IRS now? If yes, then how much on a 20K?