If it was "a pineapple" then it would be "ένας ανανάς"
The "ν" you see at the beginning is to point out that ν=n, just a letter. And then they give us the word "ανανάς" so that we can see the letter "ν" in action.
I think I understand what the creators are going for, something like childrens' textbooks, but they usually use the first letter of the word. "α για ανανάς" or however the Greeks would say it might be a better, less confusing approach?