The NOW function returns the current date and time, updates continuously whenever you open the worksheet.
The NOW function has no argument.
To get the current date without the current time, use the TODAY function.
Google Sheets uses the 1900 date system and stores date as sequential serial number, the first date is 1/1/1900 and its serial number is 1. Similarly, current date is 03 Jan 2020 and its serial number is 43833 because it is 43832 after 1/1/1900.
Numbers to the right side of decimal number of a serial number represent time and left side represent date. For example, the serial number 0.10 represents the time 02:24. For illustration, see the 2nd example mentioned above.