Just to add to what others have said - it’s a historical thing in Baltimore that is very common. You just pay a small amount twice a year but as a matter of Maryland law the other party doesn’t have any real rights or anything over the land as long as you pay. You also have a statutory right to redeem it so you own the whole property in fee simple, but it’s usually cheaper to just pay the ground rent (and your mortgage company is generally the one paying it for you out of your payments).

Some non-local lenders have problems with it though because to them it seems similar to buying a home built on leased land, which is often the kind of thing they won’t finance, but they may not tell you that until pretty far in the process.