The "wideband" is an oxygen sensor. It measures a wider AFR range than an OE "narrowband" O2 sensor. Such a device is useful when performing dyno pulls to correlate the engine's AFR with the power band readings. This helps a lot when tuning an ECU.
However, it's likely that the shop will simply clip it to the end of the exhaust pipe which will provide nearly useless readings as the exhast gasses will be significantly cleaned up by the catalytic converters.
If you're performing your dyno pulls just for power readings, skip the WBO2 option.