It is a fuel line bracket. Hanging fuel lines is bad. Replace it, should be about about $20 if it's even broken, I can't see that it is. If not, reinstall it, hopefully with a means of preventing it from falling off.
These pictures are from a Toyota, but very relevant to you:
Good:
Fuel line bracket good.jpg
In this one, the bracket at the bottom/rear is broken in half. At the top/foreground note the stud. A bracket fell off; that's what you'll see looking under your car. Look for 4 pipes kinda loose with a stud between them, and figure out how to get your bracket to stay on. Replace if necessary.
Fuel line bracket bad.jpg