The introduction of the nanoVNA has made a tremendous impact on the DIY community, students, and the amateur radio community.
There are several reasons for this: (1) extremely versatile - does the work of several instruments, (2) user interface - color, graphical based, (3) portability - lightweight and power miser, and (4) the most enjoyable reason - relatively low cost. Number 4 is the reason a lot of nanoVNA users have more than one in their kits.
So, what's the best way to learn about the nanoVNA? By watching Youtube videos! There are many videos on this subject. Here are some of the most viewed videos. Be sure to comment on which video you thought was best. The last link is to a PDF tutorial. It's good - even for a translation from Japanese.