"Hills" can mean different things to different people. If your idea of a hill is what gets climbed in extreme off-road 4x4 or motorcycle trials riding or the like, no, the BX is not meant to travel extreme grades, just like any other tractor.
It can handle moderate grades, as others have described. If anything, there is abundant horsepower. It is just about impossible to bog the engine and you will run out of traction instead of power, even when on hills. The tractor itself has a low center of gravity, but with the FEL, backhoe or attachments on, the dynamics change and it can be tipped if you are not careful.
Speaking of being careful, be sure you have the right weight distribution, the right tires and avoid cross-slopes if at all possible. Always use 4wd low range on hills... going up or down. Keep the bucket low when transporting material. If you have lots of material and long enough distance to travel, consider some kind of trailer instead of just the FEL.