If you are interested in some particular file only then you can find this info in the Solution Explorer (typically, the pane shown on the left edge, but may be customized to be shown elsewhere): just keep clicking on the hollow right-pointing triangles to the left of the filename first, then to any namespaces, classes enums and so on. If Solution Explorer is not shown, go to the View menu and select Solution Explorer. But if you want to inspect the whole project then there is Class View as well (selectable from the View menu).
Also, typically there is a Navigation Bar at the top edge of each source window. If Navigation Bar is not shown, go to Tools, Options, Text Editor, All Languages, General, and tick the Navigation bar checkbox.