Here's why:

* Relative dating uses principles like superposition (older rocks are found below younger rocks) and cross-cutting relationships (a rock that cuts through another is younger) to determine the order of events. It tells us which rock is older or younger than another, but not how many years old they are.

* Absolute dating uses radioactive decay to determine the actual age of a rock in years.

Therefore, the relative age of a rock tells us its position in the geological timescale, but not its specific age in years.