PHP is easy to get into because of the simple (and tolerant) syntax and extremely simple static typing system. The weak typing also means it's easier for beginners.

It does require twice the lines of PHP code to make a Ruby or Python program equivalent, or more if you add phpdoc and static types though, so it is easier to read/write Ruby or Python, but only after learning the details of the language. Ruby's syntax is very expressive but very complex if you don't know it by heart.