The sun sign has two parts. In the first part of sun, you make a circle with your index finger up above your head and a bit to its side. In the second part, start with your fingers and thumb together, angled downward, and then spread them apart, like you are shining a lamp down on yourself.
Teach your baby the sun sign when you go outside on a sunny day. "See the sun."
The sun flash card is a nice way to teach your baby without blinding them!