Deductions & credits

Assuming that  you are referring to is the business code.  You can select Look up my business code on that screen and TurboTax will give you a list of business categories on the right that you can choose from. When you select the business category, there will be a list of business codes, so choose the one closest to the type of your business.

Review the TurboTax articles Reporting Self-Employment Business Income and Deductions for more information on business deductions.