SWITCH( expression, value1, result1[, value2, result2][, … ][, default_result] )
expression is a text, numeric, logical or date input or reference to a cell.
value1, value2, ... is any value or reference to a cell. Each value must have a result given.
result1, result2, ... is any value or reference to a cell.
default_result: any value or reference to a cell that is returned when there is no match.
If no value equals expression and no default result is given, a #N/A error is returned.
=SWITCH(MONTH(A3),1,"January",2,"February",3,"March","No match") returns "January" when A3 contains a date in January, "February" when A3 contains a date in February, etc.