Ok I have read what advanced sensors does and I know how good the b wing is but why do I keep hearing people saying this combo is really good?

Please bring light to my darkness.

The reason this particular combo is so good is because the B-Wing has Barrel Roll as an action. This means that, before you move, you can barrel roll, then do your maneuver, or do your barrel roll after your movement. If you move after the enemy with this combination, it means you can easily get out of arc or avoid a blocker. It gives you a lot of mobility options you wouldn't have without advanced sensors.

Because you can execute red maneuvers and still get an action on the same turn, or maneuver around asteroids without hitting them, etc etc.

it lets you barrel roll before you move, so you have more options where you are going to end up. good for getting shots, avoiding arcs, and most important....not getting blocked. plus it is fun to use

( said in best southern preacher accent ) I see the light!!!

Basically, it's two-fold.
You can use a mobility-action before moving (Barrel-Roll is great, and for 4 points more you can add Boost as well).

The B-Wing's dial is actually superb if you can ignore the most painful aspect of red maneuvers (the Action Loss). This lets you do a regular Target Lock or Focus before you move, even if you do a Koiogran ;-)

Yep as others have said, it is the barrel roll. Particularly if you barrel roll to the side and back and then hard 1 or 2 turn, you will cover the same amount of distance as it you'd done the turn and then used a 1 boost forward. Even better if you combine it with PtL and Engine Upgrade as you can then boost, barrel roll and then do a green maneuver to clear the stress that you just generated.