What is a "weep hole"

[96C280]

Was wondering what the water pump weep hole is and what its purpose is.

The coolant in my 96 c280 was belched out today. I parked the car and 45 minutes later noticed a long puddle of coolant by the car. The coolant overflow tank was empty and I noticed some of the coolant in a little catch basin under the water pump.

Any ideas on what the situation is? Filled it up with some water plus coolant and there is no further evidence of leakage after a couple of trips (total: 10 miles).