Hello everyone, been reading many questions and answers about light switches but it's not exactly as the problem I'm facing... So I'll try and be specific and clear...

So this is a new house, we moved in a week ago, so I wanted to change the regular switch in the bathroom for one with a moving sensor so that when you walk in the bathroom it turns on automatically. So my sensor switch has red black and ground wires. When I removed the regular switch well I kind of was puzzled and this is not a 3 way switch, it's only to turn on the bathroom light. (there is an other switch perhaps 5 inches below that controls an air exchanger).
So in the switch box, the 2 whites are together, 1 black on one side, 1 black in a profit hole, 1 red in the other profit hole and to my surprise, the green screw isn't used but I do see in back of box both grounds from wires screwed properly.

So how do I connect my new switch.
Thanks in advance..

Connect the ground wire from the switch to the ground wires in the box.
If the instructions specify which wire of the new switch is to be used as input (red or black), connect it to the two black wires with a wire nut. Connect remaining wire to red wire of switch. That is assuming that the two black wires (under the screw and in the profit hole) are in proximity to one another.