Description:
Returns an array with unique values. Note that this is an array formula!. To enter this formula select the cells where you would like
to display the unique list of values. For example B1:B10. Then enter the formula, e.g. =Unique(A1:A100). Press Alt-Enter to confirm
the formula. Excel will display {=Unique(A1:A100)} indicating it is an array formula.
Source : Range of cells to find the unique values in.