[GA] Employer says it's "HIGHLY illegal" to discuss pay

I work for a very small company that has a lot of drama to put lightly. In a heated message to all of the employees, my boss stated that it is "HIGHLY illegal" to discuss pay and this is grounds for immediate termination without prior notice. A quick google search says otherwise. I don't know if she's trying to pull a fast one to get us to not talk about pay or if she's just dumb.

Either way, I know they're working on an employer handbook. If they put a policy like this in a handbook is it a forcible policy if you agree to and sign the handbook?

I haven't discussed my salary and don't really care but I'm curious about the legality of the statement if it's in a handbook that's been signed by you.