No secret. If you count the number and the arguments that are following, separated by a comma, you see that the 1st part containing the numbers is defining the layout, and the 2nd part is just filling the data in the "fields".
The minus says it is left aligned, the 3 says the column is 3 characters wide, and the value supplied should be taken as a
s which stands for "string".
And so on...
I have just checked how broad the columns of the heading and your input file is and have defined them for the header as well as for every line that will go through awk.
printf works like this in shell, C, awk, ..., very handy for
printing
formatted