With raytracing turned on FireFly will render the number of bounces that is set in the render settings. Raytracing will trace or follow the rays of light through each bounce that is specified at render time. BUT, each bounce increases the amount of time the render will take. Too many bounces will make a render take prohibitively long. Objects can be excluded in their properties tab.

lmk

Probably edited for spelling, grammer, punctuation, or typos.