reference is a cell reference, entered either directly or by specifying a range name. If the reference consists of multiple ranges, you must enclose the reference or range name in parentheses.
row (optional) represents the row number of the reference range, for which to return a value.
column (optional) represents the column number of the reference range, for which to return a value.
range (optional) represents the index of the subrange if referring to a multiple range.
returns the value at the beginning of the A1:B6 range.
Parent topic: Spreadsheet functions