Question: Can AirPort Express act as a bridge?
Answer: AirPort Express can act as a bridge in three different ways:
If you have an existing wired network, it can bridge this network to wireless clients.
If it is set up as a WDS remote or relay station, it can bridge the wireless network to wired clients.
If it is set up as a WDS remote or relay station, it can bridge the wireless network to wireless clients (or "wirelessly extend" the range of the network).