Your tax info is saved in the files that TurboTax creates and saves on your machine. These files are named with your name, *TT, and the tax year. So, for example, my tax file from tax year 2017 would be something like Turbotaxtara.TT17.
If you started preparing a return on one computer and then decide to move to a new computer, you'll want to copy all the *.TT17 files from your old computer to your new computer. Then, you'll be able to pick up where you left off.