The Status Bar is located at the bottom of the VS Code interface. It is used to display information about the opened project and the files you edit, as well as actions you perform, for example copying to clipboard.
The extension adds several features to this section: source control, RTT and serial connection status, extension status, and its own custom notifications in the standard Visual Studio Code notification area.
Depending on other extensions and your custom configuration, your Status Bar might look different. It can also change color to show different types of notifications.