Learn Turkish: Kapı kapalı değil, açık. - The door is not closed, it is open.

In Turkish, değil always comes after the noun or adjective it makes negative. While in English you say "not closed", in Turkish you say kapalı değil (literally "closed not").

Where is the word for "is" in this sentence?

Turkish doesn't use a separate word for "is". For "he", "she", or "it" subjects, you usually don't need to add any verb ending at all. So kapı kapalı değil naturally means "the door is not closed".

The English translation says "it is open", but why is there no word for "it" (o) before açık?

Turkish often drops pronouns like o ("it") when the subject is already clear from the context. Since we just established we are talking about the door, simply saying açık is enough to mean "it is open".

The words kapı (door) and kapalı (closed) look very similar. Are they related?

Yes! They both come from the same root word, kapamak, which means "to close" or "to cover". Noticing these patterns is a great way to remember new vocabulary.