Command + H (Mac) | Control + H (Win) can be used to quickly toggle between viewing and hiding a variety of items in Photoshop including selections, paths, guides, grids and more. In order to control what features are shown/hidden, choose View > Show > Show Extras Options.
Note, the first time you use this shortcut on the Macintosh, Photoshop will display a dialog asking “Would you like to use Cmd-H to hide Photoshop (Mac standard), or to hide/show selections, guides, etc. (Photoshop traditional)? Click “Hide Extras” unless you want to “Hide Photoshop” every time you use the shortcut.
If you do choose to “Hide Photoshop”, you can change this behavior later by choosing Edit >Keyboard Shortcuts. Set the “Shortcuts For” to Application Menus and toggle the disclosure triangle for the View menu. Scroll down to Extras, change the Shortcut to Command + H and click Accept and then OK.