Returns the month for the given date value. The month is returned as an integer between 1 and 12.
Number, as a time value, is a decimal for which the month is to be returned.
=MONTH(NOW()) devolve o mes actual.
=MONTH(C4) returns 7 if you enter 2000-07-07 to cell C4 (that date value might get formatted differently after you press Enter).