It's a bit hard to "get it" without trying it. Basically, it's just columns of clips/loops that you can trigger in various ways, with or without quantize, a row of clips at the same time or give the clips various properties to make them automatically change into another clip at a certain point. It's what gives Live it's name; you can practically play the clips like an instrument.
My more electronic stuff these days start from the session view 100% - I build a bunch of loops that sound good together, then hit record and jam out a rough structure with the clips - all this gets recorded into the "arrangement" (ie. Live's normal linear view), along with any realtime edits of effects or the clips themselves. It's simply a fun way of making music with the computer.