SQL round is a mathematical function that rounds a number to the specified precision.

The syntax for the SQL round function is:

```
ROUND(number, decimal_places)
```

Where the number argument is the value to be rounded and the decimal_places argument is the number of decimal places to round the number to.

If the decimal_places argument is omitted, then the number will be rounded to the nearest whole number.

For example, if we wanted to round the number 123.4567 to three decimal places, we would use the following SQL:

```
SELECT ROUND(123.456789, 3) AS "Rounded Number";
```

which would return 123.457.