What's this device?

I have never seen this before.

Low pressure switch,shuts compressor down if pressure in system gets lower than fixed setting.

Post a picture of that without the arrow please!

There is something strange in that photograph.

What r those unprotected orange wires and where is the insulaton on the refrigerant line?

Low voltage cable, which is permitted to remain unprotected. Not exactly a “workmanlike” installation, but no special hazard either. The worst that will happen if that cable is damaged is that the a/c won’t run.