1. To set someone or something at a position to the rear of or backward from where they were. A noun or pronoun is used between "place" and "back." Why don't you place your desk back a bit so that you're closer to the radiator? We need to place the supporting actors back about five paces, or they'll be in the way of the leads.
2. To return something to its original position. A noun or pronoun is used between "place" and "back." I was placing the vase back on the mantelpiece when it slipped out of my fingers and shattered. Be sure to place his books back where you found them!
place something back
1. to move something backwards. Place this chair back a little. It is in the walkway. Would you please place the boxes back so there is more room to get through?
2. to return something to where it was. You found it on the table. Place it back when you finish. When you finish examining the book from the shelf, place it back.