Question

what is ohms law and what is the si unit of it

Answer 1

The potential difference, V, across the ends of a given metallic wire in an electric circuit is directly proportional to the current flowing through it, provided its temperature remains the same. This is called Ohm’s law. 
Its SI unit is ohm, represented by the Greek letter Ω

Answer 2

Hello....

Ohms law " when the thermal state of the conductor is not changed the potential difference across the two terminals directly proportional to the applied electric current "

The SI unit is ohm ( in the photo) ..

Hope it is useful for you...