$SIGN can mean different things depending on context:

In programming / variables

$ is often used to indicate a variable (e.g., in PHP, shell scripting).

$SIGN would be a variable named SIGN.

In finance or crypto

$SIGN could refer to a ticker symbol for a cryptocurrency or stock (if one exists with that name).

In general text

It might simply mean “sign” (like a symbol or indicator), with $ added for emphasis or style.

If you tell me where you saw $SIGN (code, trading, app, etc.), I can give a more precise explanation 👍