I understand that you may not know the commands you are told by strangers, but many of these are tools are meant for professionals. ffmpeg, for example, is used by many industries and companies worth millions of dollars to handle production workloads. They often have documentation to tell you what they do, though

There’s a manual for ffmpeg for example: https://ffmpeg.org/ffmpeg.html

Here’s imgemagick’s documentation: https://imagemagick.org/script/magick.php

Obviously you won’t understand any of that because you don’t know the command line, but for those of us who do understand it and can use it, it’s very informative.

I think handbrake is a gui wrapper on top of ffmpeg, but I never used it, I just memorized the ffmpeg commands and can type so much faster than i can click.