WAV is raw, uncompressed PCM audio — the format every editor, DAW, sampler and CD authoring tool accepts without complaint. This tool converts your audio, or the soundtrack of a video, to 16-bit WAV so you can drop it straight onto a timeline.
It's a working format, not a sharing one: expect roughly 10 MB per minute of stereo audio. When you're finished editing, bounce back down to MP3 for distribution.
What WAV can and can't do for you
Converting to WAV stops any further generational loss — every subsequent edit and save keeps the exact samples. What it cannot do is recover detail a lossy encoder already discarded. A 128 kbps MP3 turned into a WAV is still a 128 kbps-quality recording, just in a much larger container. If you want lossless at a sane file size, FLAC stores the same samples in roughly half the space.