If the student does not have a skill level entered in the Student_Data named range, the VLOOKUP will return a value of 0. Incorporate an IF function in the formula so that if the value returned is a 0, display a blank value ("") instead, otherwise display the value returned by the VLOOKUP function.

Formula explained below

Explanation:

You have not mentioned what the Student_Data range is. But from the context, I think it's =StudentData!A3:H34.

So, use the following formula in '$F$3' of LessonData:

=IF(VLOOKUP(B3,Student_Data,8)=0,"",VLOOKUP(B3,Student_Data,8))

Then copy the above formula up to F29.

NOTE:

8 means 8th column of the 'Student_Data' table which is the 'Skilllevel' column.