1. to (make) sit apart (Think of a teacher separating two people in class and placing them in different areas.)
Opposite (closest): zusammensetzen
2. to deal with, to confront, to tackle ("sich+Acc auseinandersetzen mit" - can be about dealing with a challenge or looking into a topic or confronting something. Think of it as an opposite to ignoring, with a little "tackling" undertone, if that makes sense :).)
3. to explain something to someone, to run someone through something ("jemandem etwas auseinandersetzen" - sounds quite formal and it's quite rare.)
