Final answer:
A filled triangle to the right of a command in a menu signifies that there is a submenu available for that command, indicating that there are additional options or functionalities related to that feature.
Step-by-step explanation:
When you see a filled triangle to the right of a command in a menu, it indicates that the command has a submenu. This means that hovering over or clicking on this command will expand another list of options or commands that are part of that feature's additional functionalities. This is common in many software applications where complex features require grouping related functions together. For example, in some programs going to the "Tools" menu and then accessing the "General Controls" submenu might reveal options such as the command to show or hide the command line, among other settings.