The difficulty of learning a language is partly due to the complexity of its grammar. The grammar of every language is complicated in its own unique way. Try to explain the laws of English, such as when we can say "a girl" but also "the girl" and "girls" but not "a girl"; if it's difficult to express, just imagine how difficult it must be to learn! (Those who have taken English courses understand what we're talking about!)
Arabic has a lot of grammatical features that are very different from what we have in English. Let’s take the following as an example of this:
In English, we say things like “I write,” but “she writes.”
Arabic has the following forms (for starters, just in the singular):
I write: 2aktub / أَكْتُب
You (masculine) write: taktub / تَكْتُب
You (feminine) write: taktubiin / تَكْتُبين
He writes: yaktub / يَكْتُب
She writes: taktub / تَ
As you can see, English and Arabic have an intriguing distinction. English only actually has several verb tenses depending on who is authoring the sentence—I, she, etc. Depending on whether a male or a woman is performing the action, Arabic has a different verb form. When studying Arabic, an English speaker needs to make a new place in their brain where they can recall, "Okay, when I'm forming verbs, I need to think about gender, too."
Naturally, if you've completed a Duolingo course, you've probably encountered phrases like "You run every day." What would that be translated as in Arabic? Although we aren't sure if we are speaking to a guy or a woman, it still matters to the verb we are employing! We have structured phrases in our Arabic class so that they convey just enough information to make the grammatical differences evident. Our first lessons cover a variety of Arabic names so that we may later identify the learner's conversation partner when they inquire, "Where do you live, Rania?" or Does Omar own a cat? They can practice enough in this setting for them to begin to absorb these gender tendencies.