Which languages should i know before learning php?

Answer 1

html

Answer 2

html
css
javascript

At least the lessons here on sololearn. They are quick and easy, giving you some basic skills to understand what happens in web pages organisation. Then you will have a "landscape" vision and you will be up to choose on what part of this landscape you want to specialise deeper.
Good sololearning !

Answer 3

You can start off right with PHP, if you're feeling yourself more like server-sided developer.