Taxable income?

How much do you have to make in a year for it to be "taxable income"? I only worked a month cuz I have a baby, and her father said I didnt have to work, but this summer I did just for a month cuz I was allowed to bring my daughter with me and I only made $580...turbo tax said it wasnt a taxable income? How much to you have to make to file taxes?