Hi and welcome to the ExcelGuru forums.
The function one would use to call the cells contents and have it interpreted as a range is called INDIRECT, but I don't think you should use it. INDIRECT is an expensive function to use because it is volatile. And in your example I don't believe it is necessary.
Instead rather look at COUNTIFS, which allows you to perform a multi-conditional COUNT. I have attached a sample where a user inputs a date and COUNTIFS is used to yield a count of al occurences for that date, and for any individual chosen.