That's how you can write the English plural s in Korean.
Remember that you can't write ㅈ (or any other consonant) by itself, it needs to be followed by a vowel. So, the neutral ㅡ is often used in such cases.
Another example with a different consonant, Starckbucks: 스타 벅스
I don't know the rule which decides when it should be 스 and when it should be 즈 for a final s.
즈 sound like "jeu," and they are using to signify plural
you can also use 들 to signify plural, but most of the time in Korean plurality is not specified.
you can say 용 (dragon) for dragonS too, or you can stress that there is more than one with 용들
I am using google's virtual keyboard, and I do not see a key for the first letter of 윙. What letters are in this syllable and why can I not make them?
Not sure about your specific keyboard, but usually one types, in this order:
ㅇ ㅜ ㅣ ㅇ to get 윙.
If for some reason, my comment does not make sense for your specific keyboard, I hope someone will shine in for you...
Ah! That works. I am now confused, however, as to why it sometimes has three letter blocks, and other times four? What decides that?