Consider the given reaction:
N2(g)+3H2(g)⇋2NH3(g)
What will happen if the pressure of the reacting system is increased?
Pressure is one of the factors which affects the chemical equilibrium of the reversible system. If the pressure of the reacting species is increased then as per Le Chatelier's principle equilibrium shifts to reduce the pressure. The side of the reaction with a fewer number of gas molecules will be favored.
In the case of ammonia, the forward reaction will be favored and new reaction mixture will contain more amount of the product that is more amount of ammonia.