How does concentration affect dynamic equilibrium?
Increase in concentration of reactants shifts the equilibrium position to the right, and also increases the value of the equilibrium constant.
Concentration can be defined as the amount of substance in a given volume.
So, if you increase the concentration of reactants, the number of reactants reacting to form products will rise, and so you expect to have more products(hence the shift of equilibrium position to the right)
Equilibrium constant with respect to concentration will accordingly increase, because there is an increase in the amount(and thus concentration) of the products.
Recall that equilibrium constant with respect to concentration is the ratio of the product of the concentration of the products to the product of the concentration of reactants.