WebP to JPG converts WebP images, the format many websites now serve when you save a picture from your browser, into ordinary JPG files. JPG opens in every photo viewer, editor, messaging app and upload form, including the older programs and government or job portals that still reject WebP.
The converter decodes each WebP in your browser and saves it as a JPG at the quality you set, 92% by default to keep as much detail as possible. WebP images can be transparent; JPG can't, so transparent areas are filled with the background colour you choose, white unless you change it.
A few limits. An animated WebP becomes a still JPG of its first frame. The WebP was already compressed when the website created it, so the JPG can't be sharper than the WebP you saved; a high quality setting just avoids losing more. Very large images over about 16.7 megapixels are scaled down to fit the browser's canvas limit.