In the Read Range activity, when AddHeaders is selected, the column headers from the specified spreadsheet range are also extracted and set as the column names for the output datatable.
In the Write Range activity, when AddHeaders is selected, column headers are also written to the specified range. Otherwise, everything starting from the first row of the datatable is written to the worksheet (headers are not written).
In this case, robot first sets Drug Name, Drug Company, State and Phone as column names for the output datatable, however doesn't write them in Sheet2, as AddHeaders is not selected in the Write Range activity.
UiPath Documentation Read Range
UiPath Documentation Write Range
Exam Topic: Identify and describe how activities are used to automate actions in Excel, e-mail, and .pdfs