Have you been using the air conditioner? It's the evaporator drain afaik, anyway it's normal for water to leak from there while using the air con. What happens is that a lot of moisture builds up around the evaporator from air temp difference (possibly even some ice) and it has to go somewhere.
It's normal to see a puddle of water under that area of the vehicle when you've been stopped for a while, after air con use.
