You are being asked that because you come under the rules for the kiddie tax.
That means:
In 2020 that means that you had unearned income (from investments or unemployment) of more than $1,100
You were under 18 at the end or 2020 or your were under 24 and a full time student and at least one of your parents is alive
You unearned income over $2,200 will be taxed at your parent's tax rate and the parents social security number is needed.
TurboTax will use the parent's social security number to fill out Form 8615 that will be filed with your return.