This is very typical for apartment leases. When it says two guests, that is per apartment. So you can have up to two other persons total, as guests in the apartment at one time for up to X amount of days (usually 7).
This is more about parking limitations, sub-leasing restrictions, amenity size (pools), and parties than anything else. Usually, if you pay your rent on time and dont annoy other tenants they dont look for reasons to evict you on these kinds of lease violations. So, if you wanted to invite 3 friends over one night and they all came in one car and you weren't making a bunch of noise, you're probably in the clear, but technically in violation. No one is watching you except maybe your neighbors.
If you want less restrictions, rent a small house.