This is a firefighter using a covering jet or safety jet to cool the smoke as it leaves the window. Look at the different sizes of hose, the hose the firefighter is holding is much larger than the hoses that are going up the ladder. A breathing apparatus crew has taken the smaller, easier to handle hose in to the building. they have entered using a ladder as the front door was blocked. the firefighter with the hose is ready to help the BA crew if they get in to trouble. Cooling the smoke helps protect the buildings close to the one on fire and also the fire service equipment such as the ladder