There is a lot to keep track of when coding. An Integrated Developer Environment (IDE) has features to support your work by checking your syntax and offering code suggestions.
IDE VS Text editor
A text editor can edit code, but doesn't have the tools for developing applications. There are enhanced editors that can check syntax and basic code completion. There are others that could be considered hybrid IDEs if they're pluggable.
I don't mean to split hairs, just to point out that there are some lightweight options, the full kitchen sink, and everything in between.
IDE Options
Visual Studio Code has become a major player. It looks good and works well out of the box, and has many plugins to support all different languages.
PHPStorm is a PHP specific IDE that has great support for Drupal and other web languages.
IDE Features
Opening your project directory in an IDE will set the context for the editor. Searching for code or files will look inside the project directory, and can be set to skip dependency directories like node_modules.
Debugging is an important aspect of editors, since it needs to step through the lines while executing the code.
Navigating code, jumping to interface definitions or hooks, helps you made decisions as a coder.