How to get row count for each date present in Excel

Can be done with a group by. Have a look here:

In your scenario:

prepare a datatable with the target Column structure:
Name, Date, Count
with the help of build datatable activity - Variable: dtResult

use an assign acitivty:
left side: dtResult
right side:

(From d in YourOriginDataTableVar.AsEnumerable
Group d by k1=d(0).toString.Trim, k2=d(1).toString.Substring(0,10) into grp=Group
Let ra = new Object(){k1, grp.First()(1), grp.Count}
Select dtResult.Rows.Add(ra)).CopyToDataTable