Ms. Kali - this part would be the underbody cover, engine cover, or splash shield. These are typically attached using several plastic push pins, or clips, or small 8mm - 10mm screws to hold into place. May also be a combination of these fasteners on your vehicle.
Your first step would be to get underneath the vehicle, in the front of the bumper to examine the condition of the splash shield and then determine what may be needed to repair or re-attach the part.
For example, if the plastic push pins or clips, or small screws / hardware is needed - then remove one or more holding the cover, and then take to the local auto parts store for comparison.
If the shield is broken, damaged or cracked then it should be replaced - not a difficult task at all.
Try these on-line parts resources; www.autopartswarehouse.com; www.partsgeek.com; www.rockauto.com; www.hondapartsnow.com, www.nationalautobody.com - to list only a few.
Expect to pay around $45.00-$60.00 for the underbody cover / splash shield - minus cost for the replacement fasteners.
Honda PN = 74111T2AA00
Aftermarket PN = HO1228132 (Keystone)