House built in 1920's and has four drains in the basement, one in the middle, one on the side, one by the boiler, and one on the other side.

The one on the other side appears to be made of concrete and is a 90 degree bend like a closet flange. The top of it is missing. How do I attach a new pipe to this so I can use it as a drain?

Does this have its own trap?

How do I tell a cleanout from a drain?

Thank you in advance.