WEBA does not play everywhere: older Safari and many hardware players reject it. Ogg is open and royalty-free, which game engines and open-source tools favour. A WEBA file usually holds Opus or Vorbis in a WebM container. WEBA is at home in audio on the web; OGG is the usual choice for royalty-free audio in games and on the web. Both formats are lossy, so the content is compressed a second time; start from the best copy you have.
The defaults suit most files. Under Options you can choose the bitrate and trim the start and end.
The conversion uses your browser's own video and audio codecs (WebCodecs), with hardware acceleration where the device has it; the file is read from disk as it goes and can be up to 2 GB. Where the browser lacks a codec, the page falls back to the compatibility engine. OGG is written at 160 kbps unless you choose another bitrate.