What do you mean, no overnight?

There is no need to spend the night somewhere. "Don't spend the night" means that you don't need to spend the night somewhere. It is usually used to describe a service or scene, which means that you can complete the required things or activities in one day without spending the night in a certain place. For example, a hotel provides a "no overnight stay" service, which allows guests to stay overnight during their stay in the hotel and only needs to pay for the time period of stay.