Right now, the English text is, "Chunked uploads for files over 1MB in Upload Wizard". Besides the size being wrong according to T61906, it doesn't really give the user any reason to check the box.

My understanding (see e.g. https://commons.wikimedia.org/wiki/Commons:Maximum_file_size) is that it raises the upload size limit to 1000 MB. That's a key user-visible change, and should be mentioned (ideally using a parameter).

I think it's also meant to allow more reliable uploads (may not worth mentioning at least while it's considered "experimental").