For the synthesis of ammonia $N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$, increasing the pressure on the system at equilibrium will:

Count gas-phase moles on each side. Left: $1 + 3 = 4$ moles. Right: $2$ moles. Increasing pressure pushes the equilibrium toward the side with fewer gas moles (Le Chatelier in action). Here that is the right side, producing more ammonia. This is exactly why industrial ammonia production (Haber process) runs at high pressures around $200$ atm. The catch is that heating speeds up the reaction but shifts it the wrong way (the forward reaction is exothermic), so the process picks a compromise temperature near $700$ K.