TurboTax Business is the TurboTax program that is capable of preparing a Form 1120-S for an S corporation.
TurboTax Business is not available online nor is there a Mac version; the program must be installed and run in a Windows environment.
See https://turbotax.intuit.com/small-business-taxes/
If you are not familiar with pass-through entity taxation, have never prepared a tax return for an S corporation previously, and/or you have a complex tax scenario, you should consider professional guidance.