You are self-employed in the United States. The income that you get from freelancing is U.S. income, not foreign income. The fact that your client is in another country doesn't matter.
The tag below your question indicates that you are using TurboTax Premier Online. In Premier you cannot enter self-employment income without a 1099-NEC, and you cannot enter any business expenses. You have to either upgrade to TurboTax Self-Employed or use any version of the CD/Download TurboTax software. If you use the CD/Download software, you should use TurboTax Home & Business (not TurboTax Business, which is a different product), because Home & Business will give you more detailed guidance and help for reporting self-employment.
Does your German client pay you in U.S. dollars? All amounts that you enter in your tax return have to be in U.S. dollars. If you receive payment in another currency you have to convert the amounts to dollars.
