Honda Civic 2014 Air Box - What is the type of bolt and socket needed?

Not sure why you'd be interested in the type of bolt ... as in, why does it matter? Sorry, I'm not trying to be flippant about it, it's just an odd question. It's a bolt with a large flange on its head. It passes through a rubber grommet, which is why it has the large flange on it. It doesn't require a special socket, if that's what you're worried about?

As for the size, I don't have direct knowledge of it, however, as Moab alluded to in the comments, it's most likely a 10mm. The old adage of Honda putting their cars together with 10mm bolts only is not far off the mark. Other Civics I've worked on have used a bolt with a 10mm head on them to hold the airbox down. I doubt anything has changed in that department. If you have a set of metric sockets on a 3/8" drive, you should have the right socket to attack this ... unless it is like most any other socket set when working on Japanese cars where the 10mm seems to always evaporate. :o)