I don’t know what a .webp file is but I don’t like it. They’re like a filthy prank version of the image/gif you’re looking for. They make you jump through all these hoops to find the original versions of the files that you can actually do anything with.
The B is silent so it’s pronounced “We Pee”
There’s actually a transparent t at the end (as .webp supports transparency), making it pronounced “wept”