Depending on the report type and the data stored in the system, your results may contain multiple rows of data for each column.
For example, if you run an Employee Profile report and select the columns - First Name, Last Name, Language, and Speaking Proficiency - your results could have multiple rows for a single person if that person has entered multiple languages in their profile.
This concept is sometimes difficult to grasp. The number of rows in your output for each form or person depends entirely on the fields selected in the report. If you run a report on Performance and select fields like Competency Name and Competency Rating, you will get a separate row in your output for each competency on the form for each person. Other SAP SuccessFactors reporting solutions such as story reports have more options for adjusting the visualization of this type of output.