What it does is create a “Reps” column with the formula range(int($Number)) and with the type “ChoiceList”. It produces a list of values, as many as specified in the Number column.
Then another widget shows a summary table which groups the data using both “Name” and “Reps” columns. It includes a row for each combination of Name and a value from that generated list. So you get each name repeated Number times. You can hide the helper columns to make it prettier.
A big limitation is that the resulting summary table doesn’t hold data, only formulas. (Essentially that’s because rows may disappear from it when the original data changes.) So if you need to have other data associated with each repetition, you’d need to copy-paste the generated column of names into another table.