Learn Farsi: من شب خیلی خسته هستم.

In Farsi, general times of day like shab (night) or sobh (morning) don't usually need a preposition like "at" or "in". You just place the time word directly into the sentence as an adverb.

Why does shab come right after man instead of at the end of the sentence like in English?

While English often puts time at the very end of a thought, Farsi time words usually come very early in the sentence. The standard spot for time words is right after the subject. So the natural flow here is Subject + Time + Adverb + Adjective + Verb.

Could I just attach a short ending to say "I am" instead of using the full word hastam?

Absolutely! In spoken Farsi, people often shorten hastam to just the ending -am. Since khaste (tired) ends in an invisible "e" sound, it becomes khaste-am. Both forms mean exactly the same thing, but using the full hastam is a bit clearer for beginners reading written text.

Does kheyli always have to go right before the adjective?

Yes, just like in English! The word kheyli (very) needs to sit right before the describing word it makes stronger, which in this case is khaste (tired).