Equilibrium
N₂(g) + 3H₂(g) ⇔ 2NH₃(g)
If the concentration of the reactants is added, the system will reduce the concentration of the reactants by shifting towards the products and vice versa if the concentration of the reactants is decreased the system will shift towards the reactants.
ammonia is removed from the reaction mixture ⇒ it means the ammonia is reduced then the equilibrium shifts to the right