Ahh OK. No one ever really uses levelling in that sense - it's mostly used on forums when people are trolling each other. So if someone posts a thread like "should i fold aces preflop?" then within the first few replies someone will more than likely ask "level?"
I think moving through the levels progresses as you build on your game. When you play against an opponent who thinks at a certain level, you should be altering how you play too. There's no point trying an
bluff which
should fold out two pair if your opponent is thinking on the first level, just about his hand. As you learn to hand read better and interpret bet sizing, and generally as you play more
hands, you will find yourself thinking about more things like "i think he normally has xx range", which is essentially you moving up the levels