Depends on the language I guess.

I read it as "repeat the string Hello thrice and then add a comma and space". It's not really clear that "repeat" returns a list.

A C# equivalent would be:

     String.Join(", ", Enumerable.Repeat("Hello", 3))

Here it's easier to see that Repeat returns an Enumerable object.

Using an Extension Method, it's easy to see how someone could mistake the output:

https://ideone.com/DuIvZN