The term frame rate and FPS are often interchangeable. FPS stands for frames per second and refers to the number of video frames that display each second in a stream or other video source. This term is the same as frame rate.
Using your encoder, you can control how many frames per second a video has when broadcast over DaCast. The human eye is well equipped to see over 100 FPS, although the defacto standard is often around 60 FPS. Some would argue this has been moved to 72 FPS with the advent of more tech heavy setups.
As a rule of thumb, you can get away with lower FPS (which would also lower the amount of bandwidth you are using) if you are streaming low motion content. If there is heavy motion, you will probably want a higher FPS to make the motion feel more fluid.