Did someone give you a W-9 to fill out? Or ask you for one?
Basically, A W9 only needs box 3a and your ssn or EIN if you have one. And of course your name and address. You do not need to fill out lines 2, 3b and 4. For 3a you probably need to pick the first item, individual/sole proprietor. Someone needs your SSN/EIN to pay you as a 1099 Independent Contractor instead of a W2 employee.
IRS W-9
https://www.irs.gov/pub/irs-pdf/fw9.pdf
IRS W-9 Instructions
https://www.irs.gov/pub/irs-pdf/iw9.pdf
