What is Energy? It keeps saying "You don't have enough Energy!" what does that mean?

To grow and sell you need to keep your Energy going. There are many ways to achieve that. An easy way is to smoke up with clients which will boost your Energy and your respect at the same time. You may also notice that some of your clients have items that you can buy from them that will provide Energy boosts. Another way of getting extra Energy is sharing the game with friends or watching a video.