We have in total 20 observations.
We notice that the least value is 0 and the greater one is 7, this means that the range of the data is:

Now, we know that we want four intervals this means that we have to divide the range in 4 equal parts to find the length of each interval:

Now that we know the length we can construct our intervals:

now we need to count how many of the observations are in each interval.

Then the table is: