Hi,
it looks like a temperature sender and if you don't have another gauge to connect it too then I would just ignore it.
If you want to confirm it is a sender unit, connect a multi meter to the spade and earthed to the engine and set the Mm onto the Ohms setting and with the engine running watch if the numbers start going down slowly or if nothing happens until around 80 degrees and then the numbers drop to near zero almost instantly. This will tell you if it is a sender or a switch.
Terry