It was written there that one must not waste any time doing things that will not cause oneself to gain ahead of the others. This means that everything that the Machiavellian does should coincide with his goals and his plans in life. If there are some things that will not fit in with his plans, then he should not bother with it anymore.
This book is actually quite controversial as it has been spread out from one place to another back in the 1500s. It is still something that businessmen and those who would like to become more successful try their best to learn. They start to become more conniving and calculative about their actions in order to get ahead.