ADSR stands for 4 things:
Attack
Decay
Sustain
Release
These four basic parameters affect your sound envelope in different ways.
Attack, Decay, and Release are all "time parameters" which basically just means that they automate the time of the sound wave in one way or another. Sustain is a level parameter, affecting where the volume is held at:
ATTACK: adjusts the time in which your sound fades in from when you play your note. the higher your attack value, the longer it will take your sound to fade from minimum to maximum. 0 attack means that your note will not fade in at all and will play at its highest level upon midi interaction.
DECAY: The decay will adjust how long it takes for your sound wave to fade from your attack level, to the level your sustain is set at.
SUSTAIN: The level your soundwave will stay at until you let go of your midi note.
RELEASE: Controls how your soundwave fades out when you let go of your midi note.
Here is a video of some weird arab guy explaining this:
In this video he also explains pitch and cutoff parameters:
Pitch: modulates pitch (no shit)
Cutoff: modulates how long it takes till your filter cuts off.
Try this shit out in your favorite synth and see what happens.