Question

The relative velocity of two cars is 10 m/s what does it mean​

Answer 1

A simple example would be where the motions of both bodies are in the same straight line - for instance, two cars travelling along a motorway. If both cars are travelling in the same direction, one at 25 ms-1 and the other at 35 ms-1 then their relative velocity is 10 ms-1 (by vector addition).