@Fmbalbuena In short, undefined behaviour that isn't worth exploring while still learning Jelly
Long: + will vectorise the same as with lists of integers, and will concatenates two characters. Multiplication of two strings will error. However, doing arithmetic commands on strings will result in "Python strings" rather than "Jelly strings" and once you introduce Python strings to a Jelly program, you'll get undefined behaviour
It's clearly a modified range, with 7 elements, and each one, minus 7, is 1, 2, .... So just generate the range [1, 2, 3, 4, 5, 6, 7] and add 7 to each