The lpf is a Low Pass Filter. It keeps all frequencies but the bass notes (allowing low notes to pass) tones to from getting to the speaker.The hpf is the High Pass Filter. It keeps all frequencies except the highs (allowing high notes to pass) from getting to the speakers.
Full means whatever is input to the amp is amplified then output with no processing done in between.
Mono can be attached to more than one thing. If you bridge two stereo amplifier channels into one channel for more output then you've changed that output to mono as it is but a single channel rather than two.
Mono can also be applied to an amplifier that only has one single output channel as opposed to 2, 4, 5, or 6 channels. What exactly are you asking here?