You got bid and ask prices with their respective sizes.
The top row is usually important. Others may be fake. Watch for the sizes changing fast without enough transactions (time n sales) - those bid ask sizes could be fake too.
Usually:
Thick bid, thin ask - some buys take out the ask, a lot more sales needed to take out the bid - so on same no of transactions on either side, the PPS goes up.
Thin bid, thick ask - vice versa
Its quite helpful when there is more volume. On moments of less volume, MMs can pull the plug on you anytime - it can go either way - I was just watching the 2.03 - 2.05 zone on FNMA sometime back. Didn't get in for that reason
Hope that helps