A hotkey (or accelerator key, shortcut key, keyboard shortcut, hot key, key binding, keybinding, key combo, etc.) is a key, or set of keys, that performs a predefined function. These functions can often be done via other, more indirect mechanism, such as using a menu, typing a longer command, and/or using a pointing device. By reducing such sequences to a few keystrokes, this can often save the time, hence "shortcut".
For shortcuts which consist of keys "pressed together", one usually first holds down the modifier key(s), then quickly presses and releases the regular (non-modifier) key, and finally releases the modifier key(s). This distinction is important, as trying to press all the keys simultaneously will frequently either miss some of the modifier keys, or cause unwanted auto-repeat
Source: Keyboard Shortcut
Store Manager for Magento has lots of hotkeys and they are changing all the time. So it's easier to understand how to find them than to learn all of them.
Store Manager has one basic modifier key - [Alt]. All regular (non-modifier) keys are on the main menu drop-down names. Regular keys are underlined letters there.
For example Orders has one underlined letter [O], so that is the regular key to enter Orders section.