driving a 1991 740T. car makes noises when making tight turns. axle? ball joints? what are ball joints? will this be expensive to fix?

 

What sort of noise, clicking or ?

JAck up front end, wheels just off the ground, lever the right wheel upward an inch or two and watch the balljoint,
its located at the very bottom of the shock, if there slop it will be visible.
About $29 each from FCP, I'd do both if one is bad, the other soon follows.
Its not difficult to do with decent basic tools , BFH and a good pickle fork.