Your choices under forward mode are bridged mode, split-tunnel, or tunnel. This is going to determine how the user traffic is forwarded to the network.
In tunnel mode, user traffic is sent back to the controller and distributed from there. With split-tunnel mode, traffic designated as internal network traffic is tunneled back to the controller while all other traffic is dropped off onto the network that the AP is connected. In bridged mode, traffic is dropped off onto the network that the AP is connected.
This is a very simplified explaination but I hope it helps.