Yep, it's basically committing to the Exchange that you will put up a bunch of bids and asks on their order book, say 50 BTC worth of each either side of the spot price, maybe 1 BTC at 1% away each side, 2 BTC at 2% etc or whatever you're happy with, in order to provide liquidity for the Exchange and anyone wishing to trade there.

Sometimes they may offer you a lower, or zero, commission rate for doing this as well.