What is the meaning of $ syntax in css?

A newbie here. Forgive me if this question is very trivial.
I came across this code snippet, and I’m unable to understand the syntax.

.row.info-row:hover {
	background-color: $color-primary;
}

What is $ in this css. Isn’t it a javascript thing? Can anyone enlighten me about this?
Thankyou in advance.

It’s an SCSS variable.