The vscode editor is here: https://code.visualstudio.com/
This is a good code editor for multiple languages. It has an extensible architecture, so although not originally designed for PHP, it has many extensions which allow it to discover the wordpress API, autocomplete PHP and generally be a good editor for wordpress code development.
The following extensions are recommended:
“WordPress Snippets” by wpprotools.io. This gives you snippets for every WordPress function, class and constant. https://wpprotools.io/vscode-snippets/
https://marketplace.visualstudio.com/items?itemName=bmewburn.vscode-intelephense-client – code completion and many other functions for PHP
Other web related useful extensions:
Bookmarks by Alessandro Fragnani
CSS Formatter by Martin Aeschlimann
Live Sass Compiler by Glenn Marks
Live Server by Ritwick Dey
PHP DocBlocker by Neil Brayfield
XML Format by Mike Burgh
You should also make sure you can install and run xdebug.