It depends.
If you are a W-2 employee, enter the information from your Form W-2 in the Income section of TurboTax.
If you receive a Form 1099-NEC or other Form 1099, you are being treated as self-employed or an independent contractor. Enter the information from the form in TurboTax in the Other Common Income section and answer the questions. You may need to pay self-employment tax on your earnings, which will be credited to your Social Security account for retirement.
Enter any cash earnings in the self-employment section as well. See this help article for more information.
If you have expenses to deduct, you may need to upgrade your TurboTax product. You will need TurboTax Premium for TurboTax Online or TurboTax Home & Business for Desktop.
See here for more helpful tips for TurboTax users who are self-employed.