Exceljet

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Extend the selection to the last cell left

Windows shortcut 
CtrlShift
Mac shortcut 

If the active cell is empty, Excel will extend the selection to the first non-empty cell to the left. If the active cell is non-empty, Excel will extend the selection on the last non-empty cell to the left. On a Mac, the command key (⌘) can be used instead of the control key.