what does "tranquila" mean in this context?

i work at a restaurant. yesterday i slipped on a thin piece of meat & one of the kitchen guys said "tranquila, mami" what does this mean?? he is from mexico.

i know tranquila (as a phrase) means to relax/be calm (or some equivalent to that) but it doesn't make sense to me how "tranquila" is used in this context.