That particular exercise can be a bit confusing, sorry about that! The idea is to learn dragon language pronunciation by spelling the English words as if they were dragon words, using the pronunciations listed in the alphabet section above.

In the dragon language, "y" isn't used as a vowel. To get that same pronunciation in the dragon language, you'd spell it as "Skei" because "ei" in the dragon language is pronounced like the "y" in "sky" or the "i" in "hi".