Civic EG

So i got a noob question...the bolts have fallen out of this and I don't know what the part is called...thanks in advance

compensator arm

is that part of the trailing arm you took off on the rear?

This is also known as the rear toe arm. Because that is how they adjust the toe in the rear, there is a slider bolt on the chassis side so make sure you put it back right where it was other wise your toe will be off on one side.