In the Device Control Presets tab, you'll see a list of all of the ways you can connect your camcorder or tape deck to the computer you're using to log and capture. This tab is essential for troubleshooting problems with logging and capturing, as it's very common for FCP 7 and a camcorder to not understand each other at first.
If you shot HDV, or HD video on a DV tape, and are capturing footage by attaching your camera to a computer, you'll most often use the Device Control Preset pictured above. "Firewire" refers to the type of cable you use to attach the camera to your editing station.