They might be talking about the "front control arm" bushings as opposed to the "lower control arm" bushings. These are fluid filled and over time they crack and leak. The bushing can be pressed into the arm and replaced at most once per arm.

As an alternative you can buy the entire arm, with bushing already pressed in.
Search the internet for "BMW X5 front control arm" and see what you find.

A good independent shop might install both arms for $200.

I installed them myself. I tried pressing the bushings in myself with a mobile press. Eventually I had to take the arms and bushings to a shop to press them in.