The old system (Debian 11) has SMPlayer pre-installed has its default media player. You can find it in the "Multimedia" category in the application menu.
The new system (Vivid Unit OS) doesn't have SMPlayer pre-installed, and you need to install it manually:
sudo apt update sudo apt install smplayer
SMPlayer has very intuitive user interface and it looks just like other media players you use everyday. After loading the audio/video file into the player, you can click the play button to start playing it.
