Learn Arabic (Modern Standard): إن الموقف غريب جدا.

إن (inna) is used to emphasize a nominal sentence. When you add it to the beginning, it forces the subject of the sentence, الموقف (the situation), to take the accusative case. The predicate, غريب (strange), remains in the nominative case.

Why is جدا (very) at the end of the sentence instead of before the word strange?

In Arabic, adverbs of degree like جدا (very) always come after the adjective they modify. So instead of saying very strange, the Arabic word order is literally strange very (غريب جدا).

If I were to read this out loud with full vowel endings, how would it sound?

It would be pronounced Inna al-mawqifa ghareebun jiddan. Notice the short 'a' sound at the end of الموقف because it is the subject of إن, and the 'un' sound at the end of غريب because it is the predicate.

Does إن always have to be translated as 'indeed' in English?

Not necessarily. While 'indeed' or 'truly' helps show the emphasis إن adds, in natural English we often just use a firmer tone of voice. You could translate this simply as 'The situation is very strange,' but knowing that إن makes it a stronger, more definite statement.