What does Pat Hand mean in poker? 

A Pat Hand in poker is a made hand that the player does not want to improve by drawing more cards. In other words, the hand already looks strong enough as it is.

How does it work?

The term is most often used in draw games. If the player already has a completed hand and does not need to change anything, they stand pat. That immediately gives some information about strength or, at the very least, the intention to show down a made hand. In simple terms, a pat hand is a hand that has already reached the desired point and does not need any further draw.