Learn Arabic (Modern Standard): هو يتعلم لغة جديدة.

You would use the question word ماذا (what - used with verbs) from this lesson. The question becomes ماذا يتعلم؟ (What is he learning?). Notice you can drop the pronoun هو (he) in the question because the يـ at the beginning of the verb already tells us it is 'he'.

Why does the verb يتعلم start with the letter yaa (يـ)?

In Arabic, present tense verbs use prefixes to match who is doing the action. The prefix يـ (yaa) is used for 'he'. If the sentence was 'She is learning', it would use the prefix تـ (taa) and become هي تتعلم.

Why does جديدة (new) have a taa marbuta (ـة) at the end?

Adjectives in Arabic must match the noun they describe in gender. The word for language, لغة, is feminine, which we can usually tell by its own ـة ending. Therefore, the adjective 'new' must also be in its feminine form, جديدة, rather than the masculine جديد.

Why is it لغة جديدة instead of جديدة لغة?

In Arabic, the adjective always comes right after the noun it describes. So instead of saying 'a new language', you literally say 'a language new' (لغة جديدة).

Where are the words for 'is' and 'a' in this Arabic sentence?