He wants to write the fraction 4 / 6 as a sum of unit fractions. It is written as follows:
1/6 +1/6 +1/6+ 1/6= 4/6.
A unit fraction has a numerator of 1 so since 4 is the numerator in 4/6 you would have to add 1/6 for four times.
Hope this answers the question. Have a nice day.
