What's "Bonus Item" in Diablo 3?

So I haven't actually played Diablo 3 in a long time, and I'm curious about the new update.

Seems like there's now a "+Bonus Item" for the new Monster Level System.

Does anyone know what's that about? What does it do?

It is explained in a little more detail later in that same article

In Inferno, in addition to increased experience, Magic Find, and Gold Find, whenever a monster dies and drops an item normally (whether it be gold, a potion, or a piece of gear), the monster also has a chance to drop an additional bonus item. The chance to drop a bonus item will scale up with each MP level as detailed in the table below.

So basically, you just get another roll on the monster's drop table. This could result in anything from gold, potion, a white item, on up to a legendary.

Its worth pointing out that the bonus item only applies to normal monsters (and apparently not all of them). So you won't get extra drops from champions/rares/bosses.