Sample Rate, Bit Depth and Bit Rate
If you have a music file and you want compress using lossy compression then the quality of the sound will go down. So if the file was originally 44 100 sample rates per second when you compress it it might 20000 sample rates per second.
For example if you listen to an Audio with 24 bits will sound crisp and clear but if you listen to the same audio but with a lower bit depth there might be a little distortion when you play the sound.
If an audio is more than 16 bits there are some sounds that the human ear can not hear.So it does not make the quality of audio sound better if it is over 16 bits because we wont be able to hear the other sounds.