Translation:The compass lets us know where our grandmother is.
Yes, but you can try to divide the sentence and practicing by segments, and forgetting a moment the well construction of the sentence in English. I mean this:
Cái la bàn ̣(The compass)
cho (to give, to provide, or maybe to offer)
chúng tôi biết (we know)
(here there is a little pause, and I think that is better to remember; I mean this pause is very helpful)
bà của chúng tôi (our grandma, our grandmother, our grannie, etc.)
đang ở đâu (where is at the moment).
Also, if you pay attention on the pronoun chúng tôi, that is a bit accelerated but still I do not know for what reason.