You could think of a buddy pounce as an alert and get an idea of the most minimal use of a buddy pounce. In reality, a buddy pounce is much like a macro, or a recorded action. When you set a pounce on someone, you can choose from a number of events, such as sign on or status change, and then you choose from a number of actions. These actions include everything from playing a sound (like an alert would do) to sending a message to the person, to executing a command. This action will occur the next time pidgin detects the event, i.e. the next time the person in your buddy list who you have pounced signs on.
from: http://developer.pidgin.im/wiki/Using%20Pidgin#WhatisaBuddyPounce
