What is meant when chemists say that the equilibrium position of a reaction "lies to the left"?

Chemical reactions are generally of two types. In many
chemical reactions the reactants combine to form products - the reactants are gone and
the products are all that is left.  Examples are when a solid  precipitate forms as one
of the products or a gas is released as one of the
products.

Another general type is when the reactants and
products are both present.  What is happening is that the reactants are combining to
form one or more products but the products are also breaking down to reform the
reactants.  In a reaction of this type,  you measure the relative amount of reactants
and products to determine whether there are more products or more reactants present in
the equilibrium mixture. If there are more reactants than products the equilibrium "lies
to the left" and if there are more products than reactants then the equilibrium "lies to
the right".  The reaction of H2 with N2 to form NH3 would be an example of an
equilibrium reaction.