This phrase is not exactly a slang but a colloquial metaphor. It literally translates to 'a woman is like a mirror, if it is touched too much it fogs up'. It's often used to imply that if a woman is given too much attention or is overly pursued, she might lose interest or her appeal might diminish.
Examples
- Spanish: No la presiones tanto, recuerda que 'la mujer es como el espejo, si se toca mucho se empaña'.
- English: Don't pressure her so much, remember that 'a woman is like a mirror, if it is touched too much it fogs up'.