Starting with Simple things that are easy to learns seems like a good idea. If anything interests you just google the names.
1. AviDemux, it a small and very simple editor. You don't want to edit in it, it is for quick trimming or for pulling out video/sound from different parts of the file. Set an in marker then an out marker and save, anything between those two will be saved as a clip without encoding them again(if output is set as copy). then that can be repeated until you have everything you want. It is also possible to append several clips into a bigger one, don't do this.
Audio tracks can easily be extracted from a video in seconds by pressing the "audio" menu up top, no need to use command line ffmpeg or anything like that.
This is the it with no video loaded. The interface is sparse but it does it's job very well.
Highlighted in yellow are the setting I recommend, trimming or extracting a sequence happens about as fast as your hard drive can handle the reading/writing if it's just copied out. Sound can also be shifted if out of sync.
At the bottom of the picture above is "configure", it can set the flag for the aspect ratio. If you captured something from VHS(4:3) the computer file might end up 16:9. Change the flag, click, it's done. Useful from time to time.
It can recompress into different formats but Handbrake is a way better and more comprehensible solution. It can be useful if the clip/video is in some shit format that cannot be cut or makes handbrake crash. If the video is meant to be part of an editing project then just pick mp4 and put the bitrate at 20,000, little to no quality will be lost, compression will be fast and the file will be huge. But it works.
Handbrake can also burn in subtitles such as .ass, I will return to those.
2. MKVToolNix, it looks like this. It does a lot of what AVIDemux does plus some other things, so it has some uses even though the interface isn't the friendliest.
Muxing/demuxing is easy, splitting both the video file into a pure video file and a pure audio file. Or muxing in more audio tracks or making subtitles part of the container instead of separate files.
It can add chapter markers as well, useful for those that wants all their One Piece episodes into in a gigantic file. MKVToolNix is a bit fickle though, it has a touch of the *ixsm.
For subbing or adding text or simple graphics there's a program called AegisSub, created for weebs by weebs to translate anime, and it is actually really good. It is a basic text editor, text can otherwise be a pain in the ass in video editor, with lots of options for styles, easy to time code things and so on. I've met people that use it a lot without knowing it is a program to subtitle anime, it's pretty remarkable.