Please note: Short Term Medical (STM) coverage is not a replacement for ACA mandated health insurance. It is solely meant as temporary coverage to provide you some financial peace of mind until you are able to enroll for ACA qualified coverage.
Day(noun) the time of light, or interval between one night and the next; the time between sunrise and sunset, or from dawn to darkness; hence, the light; sunshine. Day(noun) the period of the earth's revolution on its axis. -- ordinarily divided into twenty-four hours.
What is the Date today would technically mean you were asking the number of the day, like October the 18th. But if you were to say What is the Day today would make you be asking the name of the day, like Sunday.