What kind of income? W2, 1099 etc. You probably had withholding taken out? Do you mean no tax on line 16 or no tax due on line 35? Your withholding and credits must have covered the tax on your income. Review your return (each line) before you file. What lines don't you understand?
Before filing, You can preview the 1040 or print the whole return
https://ttlc.intuit.com/community/accessing/help/how-do-i-preview-my-turbotax-online-return-before-f...
