Visual Studio Code is becoming popular because it's free and has a lot of great features :)

I'm personally fond of Vim, but it has a significant initial learning curve so I can't really recommend it as a "beginner" editor.

Usually, operating systems come with a simple one you could use for a while (such as "notepad" on Windows). After some experience you might have a better idea of what features you'd like to have in an editor which would help to select one.

Would agree with Alena on VSC. If you are looking for something a bit more robust an IDE helps a lot. I personally use VSC and PHPStorm.