Essentially it does the same thing, reducing the dynamic range - your device obviously has preset parameters, and your friend's has more normal functionality...
Attack and sustain are terms used a lot in music to describe a sound "envelope" - to get a good understanding, just do a google of the terms, but roughly, attack is the amount of time from the start of a note to when you want something to change (ie. compression applied) and sustain is the length from when a change starts to when that change ends (or another change starts).
So a slow attack means that the sound is allowed to go on for a time before whatever the change / effect, is applied, and a long sustain means that the change is allowed to occur for a long time. So a slow attack will vary in millisecond terms, depending upon what effect / change is being applied...
They're not just used for compressors, they're general terms you'll come across a lot. Suggest you do a bit of research - there are lots of compression primers hereabouts...
And google decay and release too, you'll need to know those terms as well..
Clear as?
Cheers