convert mkv to mp4 in obs studio

in this video you can see how to convert videos recorded in obs studio from mkv files to mp4 files.
some apps or softwares does not support mkv file so converting them to mp4 is preferable as most apps and softwares support mp4 files.

obs provides an inbuilt converter called remux, it will remux the mkv files to mp4 files.
i don't know the meaning of remux but that's what i can understand by using that in obs studio.