What does プチプチ mean? I thought that it might be a sound, but it may also mean bubble wrap. I just want to clarify. Thank you very much.

{HLLL} is an onomatopoeia for the sound when bubbles (or something swollen) pop continually. It's reduplication of .

{LHHH} is the most well-known name of bubble wrap or (although it's a brand name). Obviously it's named after the onomatopoeia.