I do not understand this example, any help ?

Question

recursion example

Answer 1

Here are many good discussion on this topic in past may this help you out
https://www.sololearn.com/discuss/1386899/?ref=app
https://www.sololearn.com/discuss/1467328/?ref=app
https://www.sololearn.com/discuss/1486703/?ref=app
https://www.sololearn.com/discuss/120350/?ref=app
https://www.sololearn.com/discuss/488848/?ref=app
https://www.sololearn.com/discuss/1149517/?ref=app
https://www.sololearn.com/discuss/307407/?ref=app
https://www.sololearn.com/discuss/1581638/?ref=app
https://www.sololearn.com/discuss/1294343/?ref=app
https://www.sololearn.com/discuss/311837/?ref=app

Answer 2

And this lesson may help you to understand things better
https://www.sololearn.com/learn/Ruby/2725/?ref=app

Answer 3

Check this post to understand how recursion work.

https://www.sololearn.com/discuss/1149517/?ref=app