Now notice that this k is simply a ratio between the product concentration and the reactant concentration. So we say that if our K is greater than one, that means our reaction is favorable. If our K is less than one, our reaction is unfavorable. In other words, if it's greater than one, that means our equilibrium lies to the right. Because these guys completely react to form our products. In other words, if K is much larger than one, we have very little of our concentration of A and a lot of concentration of products, namely C and D.
Likewise, if K is much less than one, that means we have lots of this guy left over at equilibrium and very little affirmation of our products.