"On Saturdays she does not go."
Translation:Op zaterdagen gaat zij niet.
I typed in "'s zaterdagen" and it didn't accept that. The only options are "Op zaterdagen".
's zaterdag it's not a word in Dutch. The 's does not go with the name of the weekdays. It's used with 'smorgens, or 'sochtends or 'savonds etc.
That would be 'they don't go'. It is 'she doesn't go', which is 'ze gaat niet'.
That referred to the difference between zij gaan (plural) and zij gaat (singular).
In your case, generally if the sentence does not start with the subject an inversion of verb and subject takes place. I.e.
- Ik ga op zaterdag naar huis - I'm going home on Saturday
- Op zaterdag ga ik naar huis - On Saturday I'm going home