You won’t see this sign very often. I have only seen it in temples in Northern Thailand. It says “su-paap satree haam kao” which means ladies forbidden to enter. The word “su-paap satree” is lady and is not used often. And “haam” is “forbidden” which you will often see on signs.
สุภาพสตรี ห้าม เข้า (su-paap satree haam kao)