Angel Fountain is not only a pretty decoration in your farm, it is also a good source of Energy. As soon as you build it, an Energy bubble will appear on the fountain and you can tap on it to collect 40 Energy. At every 12 hours, the fountain recharges and gives Energy again.
If you use Amber Orbs on your Angel Fountain, you will get Charged Energy gift instead of the regular one. Charged Energy gift grants you 100 Energy and can be used twice in a row. (you need to wait 12 hours for the next Charged Energy gift).