This quote is saying that friendship is a very important part of life, and it is even more important than family. It is saying that if you take away friendship, what is left in life won’t be sweet. To put it another way, if you don’t have friends, life won’t be enjoyable. The quote then compares friendship with the sun. Without the sun, the world would be dark and gloomy, and it is the same with friendship – without it, life won’t be bright and happy.