It is about creating an atmosphere of warmth and comfort. A relaxing feel good mood. It is a wickless candle of sorts, a scented wax that you melt in a warming device either electric or one that uses a tealight.
When the wax is warmed up it releases the fragrance oil. The unit creates a feeling of warmth and comfort which is why many love the wax melts. If the fragrance becomes too strong, you can simply turn the unit off. If you want to add fragrance, you can add more wax melt cubes or even some home fragrance oil to increase the fragrance strength.
The beauty of a wax melt warmer is you can easily change the fragrance by cleaning out the bowl and using a different scented wax melt. To clean out the warmer unit, turn it off and a minute or two later put a cotton ball or two in the wax. These will absorb the wax enough to clean the bowl under hot water. You can also put the wax bowl in the freezer until it hardens, then pop out the wax, carefully.
It is best to invest in a good ceramic wax melt burner and one that fits your decor. Check out Claire Burke's unit. This one has clean lines, is white ceramic and simple so that it will fit in any décor, not to mention 'budget friendly'.