Do you know how many meanings the word light has?
So, let's count:
pale in colour The dress is light blue .
not weighing much The bag is light.
small/not much We had a light snack after classes.
not severe You should do light exercises.
gentle/quiet/not strong The light wind is blowing outside.
enjoyable & not serious a light joke
about food/drink a glass of light cola
a light sleep is one in which you wake up often. Someone who often wakes up while they are sleeping is called a light sleepersoil: easy to break up