You mean the ones that open on the turret? What do they do or who are they for?

The one in in the cupola is for the tank commander and the gunner also uses it to get out since he sits in front of him. The one on the turret roof on the right is for the loader. On the right rear of the turret, many tanks, HL and Tamiya included had an escape hatch here. The very first tanks didn't have one, the 46th and later tanks did.