That looks to be one of the six bolts that holds the front reinforcement plate in place - the large alloy (or steel on the 4.8is?) plate under the engine. This plate is critical for front subframe integrity.
Check that there is a bolt missing - and note that four of them also retain the sway-bar bushings. If one is missing, you are probably OK to drive to a shop but you'll want to get it sorted before driving too far.
*edit* - yellow and green arrows here: -
