Read and write ports in a register file?
A "register file" is an aggregation of registers. That is, it is one component that holds several different registers.

How many read/write ports?  Well, this depends. It can be 1 and 1, or more, according to the specific system. If you are the engineer, you can design a register file with as many read and write ports as you desire. The maximal number would probably be the number of registers in the file because there is no point in placing more read/write ports than actual registers (=memory cells).