When someone feels sads, they are not happy. They feel blue or down.
Feeling sads is not good. It means someone is feeling unhappy or low.
Examples:
She has the sads because she lost her toy.
He gets the sads when it rains.
The sads make me want to stay in bed all day.
The sads hit me when I can't find my favorite toy.
The sads are like a big dark cloud over my head.
The sads are like a heavy rock in my tummy.