This command is a shortcut to JetBrains Rider's code exploration and inspection features:
You can invoke this command from the Solution Explorer, from Structure and other tool windows. Depending on the context, this shortcut helps you access all code-exploration features available in that context.
View contextually available code exploration features
Place the caret at a symbol in the editor or select the symbol in the Structure tool window.
The Inspect This list appears.
Choose an item from the list and click it or press Enter.