The answer is the
reaction will shift to the left (toward the reactants).
Reaction is at equilibrium can be expressed as,
Reactants ⇄ products
After coming to the equilibrium, if one condition
is changed, then according to the Le chatelier's Principal, the system
will act to maintain the equilibrium by reducing the effect. As an example, if
we reduce the pressure, then system acts to increase the pressure to maintain
the equilibrium.
Likewise, if we add products into the reaction
which is in equilibrium, the system acts to reduce the effect by promoting the backward
reaction to produce reactants.