Learn Arabic (Modern Standard): السؤال الأول سهل.

In Arabic, ordinal numbers (like first, second, and third) act exactly like adjectives. Just as you put color adjectives after the noun they describe (like saying "the car red"), you put the ordinal number after the noun. So, you literally say "the question first" (السؤال الأول).

Both السؤال and الأول start with ال (al-). Is that required?

Yes! Because ordinal numbers act as adjectives, they must match the noun they describe. Since we are talking about the specific question (السؤال), the word "first" must also have "the" attached to it (الأول). Literally, it translates to "the question the first".

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

Arabic doesn't use a word for "is" in the present tense. Instead, it uses a grammar trick. Notice that سهل (easy) does not have ال (the) at the beginning. Having a definite subject (السؤال الأول) followed by an indefinite word (سهل) signals the invisible "is", completing the sentence: "The first question is easy."

If I said السؤال الأول السهل, what would that mean?

Because you added ال (the) to سهل, it now matches the rest of the words perfectly as an adjective. Instead of a complete sentence, it becomes a single descriptive phrase: "The easy first question...". Leaving the "al-" off is what gives you the invisible "is".