We emulate most of the date and time operations available in Excel. For example, to add 7 days to a date, just add the number 7, e.g.
See you next week on the @(date.today + 7)
To rewind a date by a certain number of days, just subtract that number, e.g.
Yesterday was @(date.today - 1)
To add or subtract months, use the EDATE function, e.g.
Next month's meeting will be on @(EDATE(date.today, 1))
To create a datetime from a known datetime and a separate hour, e.g.
Your next appointment is @(DATE(YEAR(contact.created_on), MONTH(contact.created_on), DAY(contact.created_on)) + TIMEVALUE("15:00"))
To change the time of datetime value, add or subtract the result of the TIME function, e.g.
2 hours and 30 minutes from now is @(date.now + TIME(2, 30, 0))