“P” traps are normally exposed OR used for a floor drain within 15 feet of a vented line.( depending on local codes) Then there are the “P” traps used under some urinals and bathtubs and THESE are not exposed BUT are placed under the fixyure. A Shower stall is also placed over P trap BUT VERY seldom are P traps placed inside the wall as they wouold be difficult to rod at that angle
In your wall ?? well that I dont know, but as to if you have a “P” trap or an “S” trap. turn yout head to the right whilst looking at the screen. The “S” trap runs down from the underside of the bowl, up, then straight back down … like a “S” on its side. The “P” trap does the same, but heads off on the horizontal plane. hope this helps