PHP stands for PHP: Hypertext Preprocessor. Which is a Recursive Acronym. It used to mean Personal Home Page because it was made by a guy at CERN for his "personal home page" you know? But since every companies back in the day used it (Facebook still does), and so Personal Home Page didn't sound that fitting anymore, they have to make up a new abbreviation meaning.
I don't know and frankly don't care about whether PHP is dead or not. I like it a lot better than react.js if I have to say.. It feels very Retro (probably because it's old.. 30 years in fact) and I also just found out it predates Javascript!
First Experience with PHP is in M4, in a Computer class? The teacher taught us basically nothing and just let us copied his code. I already was using SpaceHey back then so I did better than most at HTML and Css when he let us do whatever we want. I didn't get how PHP works back then but I learnt the Syntax.