This is what I found online regarding restrictions when entering the country, to be safe I would confirm with your hotel though:
https://www.rki.de/DE/Content/InfAZ...072020_17_45Uhr_en.pdf?__blob=publicationFile
In general people have become quite relaxed about the virus.
As a rule of thumb put on a mask in enclosed public spaces, especially trains. Toddlers are exempt, if you're planning to bring any.
Some places may ask you to write down contact info for potential tracing.
As for restaurants/pubs: you basically put on a mask every time you're on the move, but tables are supposed to be a safe distance from each other, so you can take it off once you're at your seat. There is no curfew for bars you're can get as drunk as before, but if you're trying to visit a club it will probably be closed.
A lot of places (super markets especially) used to ask people to pay cashless, but at the moment that doesn't seem to be a thing anymore.
Some places may require you to make an appointment/reservation to handle their Corona-adjusted capacity limits, so to be safe I would check the website of museums or other places you want to visit, before you show up.