From VSCode documentation:
A Minimap (code outline) gives you a high-level overview of your source code, which is useful for quick navigation and code understanding. A file's minimap is shown on the right side of the editor. You can click or drag the shaded area to quickly jump to different sections of your file.
To further improve location awareness, it can highlight which line you are on and what is selected.
From VSCode documentation:
To further improve location awareness, it can highlight which line you are on and what is selected.