Let's look at it in a dialogue.
Ali: Marhaban, Amir.
Amir: Marhaban, Ali.
In Arabic, to say "hello", you say "marhaban". To make this more clear, let's take a look at some more examples:
Fatimah: Marhaban, Amir, Marhaban Ali.
Ali: Marhaban, Fatimah.
Amir: Marhaban, Fatimah. Kaifa haluki?
"Kaifa haluki?" means "How are you", but don't worry about that quite yet. For now, focus on "marhaban".
/p b pʼ t d tʼ c ɟ cʼ k g kʼ/<p b p̓ t d t̕ q j q̓ k g k̓>
/ts dz tsʼ/<c ʒ c̓>
/β s z ʃ ʒ x h/<f s z š ž x h>
/m n/<m n>
/l ɺʲ/<l r>
/j ɥ w/<y w v>
/i ʉ u/ <i ŭ u>
/e ə o/<e ă o>
/ε a ɒ/ <ê a ô>
27 base letters + four diacritics. No digraphs.
An example of one of the ways in which you shouldn't start sentences is that this is a terrible sentence no one wants to read. Seriously, if you ever start a sentence like that, you’re fired. Clean out your desk. Go.