what is causing my van to pull to the left

Check alignment and check to make sure none of the brakes are hanging up.

its not the breaks we just fixed them. the right side was doing the same thing but the bearing went out on that side we fixed that and it stoped he checked the left bearing and there was nothing wrong with it he said something bout a rack and pinion could that be it

The rack won't cause it to pull. However, a worn steering component could.

ok what is that and is it hard to change/ fix

It could be one of several things... Tie rod, ball joing, pitman arm... They need checked for excessive play.