What does a colored dot in the Explorer View in VS Code mean?

I am unsure why my file is appearing in red font. Here is what it looks like: (https://i.stack.imgur.com/KWnoM.png)

Whenever I am trying to run a program, the program runs successfully, still it showing red font in explorer.

The red dot in the explorer tab is called a problem decoration. See also the related problems.decorations.enabled setting. The red colour is typically for error-level problems (yellow typically for warning-level, blue typically for info-level, but it can vary based on your colour theme).

Taking a look at your screenshot, you have a whole heck-ton of problems in your source code (113 errors, 5 warnings).

To get rid of the problem decorations, I'd suggest to actually fix those problems. Open up those files and you'll see red squiggly underlines where the problems are, and hover over them to see what the problem is, and then fix the described problem.

You can view an overview of all problems in the Problems Panel, which you can open with the View: Toggle Problems command in the command palette, or View > Problems in the menu bar.

The fact that you can run your program successfully probably means that you just haven't yet properly configured IntelliSense in your project. It's impossible to know what you're missing without more info. It might help you to read https://code.visualstudio.com/docs/languages/java.

^{A really stupid and bad way to get rid of those decorations in the Explorer View is to put "problems.decorations.enabled": false in your settings.json file. I don't recommend that. Fix the problems.}