This app was mentioned in 1 comment, with an average of 2.00 upvotes
There are games that learn you the logic of programming in a playful way. If he surpassed that already or want to skip he can have a go with Game Maker Studio. If he is really interested and determined, install an IDE and let him have a go at C# with tutorials. The latter is the "least fun" but he might benefit the most from it. If he can do the basics of C# he can do Unity and he will benefit from C# the rest of his life.