Learn Farsi: این شرکت ماشین من را کاملاً خراب کرد.

That symbol is called a tanvin. It is a suffix borrowed from Arabic that is added to certain words to turn them into adverbs. Here, the Farsi adjective کامل (kâmel, meaning "complete") gets an alef with the tanvin symbol to become کاملاً (kâmelan, meaning "completely"). It is always pronounced as "-an".

Why is کاملاً spelled with an alef at the end if it's pronounced "-an"?

In written Farsi, the "-an" sound for these specific adverbs is represented by adding an alef topped with the double-dash symbol. Even though you just say "kâmelan", you must include the alef in formal writing: کاملاً. In casual texting or handwriting, Farsi speakers sometimes drop the top symbol and just write کاملا, but the alef is always required.

Why is the adverb کاملاً placed right before the verb?

In Farsi, adverbs of degree or manner like کاملاً naturally sit right before the verb they modify. Since Farsi generally places verbs at the very end of the sentence, the adverb is tucked just before the compound verb خراب کرد (ruined).

Why do we need را (râ) after ماشین من?

را is the specific direct object marker. Because "my car" (ماشین من) is a specific, defined thing that is receiving the action of being ruined, it must be followed by را. Notice that the invisible ezafe vowel links "car" and "my" (ماشینِ من), and comes after that entire noun phrase.