The SKS uses a tilting breechblock operation. How does this work and what are some of the strengths?

The falling/tilting breechblock operation in a gas operated system like the SKS is simpler that it sounds. The breach block that lifts and falls during operation is what is locking and unlocking the bolt allowing it to perform its normal cycle of operation. The piston being driven by a fired round pushes back on the bolt and the breach block tilts up because it is forced to. Then when returning it falls back into place as intended. One of the biggest benefits this has is a more reliable firearm. Usually if the ammunition has enough pop to throw a bullet, it has enough gas to cycle the bolt.