A string is text that is enclosed in quotes. The quotes tell the computer that the characters in between them are not part of the executable code. There are rules for using quotes, escape clauses for some of those rules, and methods you can use to manipulate them.
In all honesty, once I got to this point I decided I’d just skip the videos and go straight to the challenges and quizzes. It was more engaging for me to have to guess or search for the methods they asked me about than it was to sit through more videos.