What does the Oracle round function mean? How to use it?

How to use the Oracle Round function (rounding) Description: Returns a numeric value that is the result of rounding by the specified number of decimal digits. SELECT ROUND (number, [Decimal_places]) from dual parameter: numbers: The value to be processed decimal_places: rounding, fractional numbers (preset 0) Sample:selec T round (123.456, 0) from dual;          Backhaul 123 Select Round (123.456, 1) from dual;          Backhaul 123.5 Select Round (123.456, 2) from dual;          Backhaul 123.46 Select Round (123.456, 3) from dual;          Backhaul 123.456 Select Round ( -123.456, 2) from dual;        Backhaul-123.46

What does the Oracle round function mean? How to use it?