"The nice popcorn"
Translation:το καλό ποπ κορν
"νόστιμο" means "tasty" "ωραίο" means "nice" or "beautiful" So you use "νόστιμο" for something eatable and "ωραίο" for something or someone that you like. You can use it for a thing (ωραίο παντελόνι = nice trousers), characteristics (ωραία ματιά = nice/beautiful eyes), the weather (ωραία μέρα = beautiful day) etc..
HINTS ON HOW TO LEARN THE MODERN GREEK ALPHABET and HOW TO GET THE GREEK KEYBOARD
And you should also look at the Greek Forum for other helpful links.
TIPS TO HELP YOU LEARN + HOW TO REPORT A PROBLEM
I often tell learners that Duolingo doesn't penalize for incorrect punctuation, capitalization, accents, and even has lee way for certain spelling errors and of course typos. But I have never said nor heard that "if you leave a space where there shouldn't be one but the answer is otherwise all correct, DuoLingo would not penalize". However, it is not impossible.
If you are saying that you believe your sentence was rejected due to an extra space..I"m speculating here since you don't give much info...then you should have left a REPORT.
Make that Report> Check the comment above yours for learning tips as well as how to make a Report.
Please give us the reference to where you were informed that leaving a space would not result in your sentence being rejected, so we can check it and possibly correct it.