Congratulations! You have just scored a critical hit on your enemy. If you can get into melee range fast enough and press the 'F' Key you will be treated to a finishing move where you kick your Enemy. Not only do you get a special graphics but also added experience. Due to the amount of experience you will want to do these finishing moves whenever possible.
When you have killed an enemy a glowing object will remain. You can target it and press the 'F' key and this will allow you to loot items or loot all. You can also stand on the loot and it will automatically be added to your inventory and will show up on the side bar for a time.
If you do not want to loot all items you can set your loot filter to a higher value to ignore different classes such as 'Junk'.