Sami has a nail studio and has to serve its customers. For each one she has to do their nails, receive a payment and pass to the next one. As you progress you can buy upgrades and will have to deal with more difficult tasks: customers will ask for more things and you'll have less time to do them.
When a customer arrives, click on the oval at the bottom to start serving her; you have to paint 5 nails with the colors she wants; to do it, click in the corresponding color varnish and then drag and drop it to the nail until it's painted. When it's ready, click the dryer and then keep the left mouse button pressed on the nail until it's dried. When you finish with all fingers, click 'done' to go back to the nail studio, where the customer pays and leaves: click on the coin to take it and then you can continue with the next customer.