Learn Farsi: مرد جوان کاپشن و کراوات پوشیده است. - The young man is wearing a jacket and a tie.

In Farsi, certain verbs that describe a physical state or condition—like wearing clothes, sitting, or standing—use the present perfect tense to show an ongoing state in the present. پوشیده است literally means "he has put on," which naturally results in the present state of "he is wearing."

How would I say "The young man is putting on a jacket" to show the physical action instead of the state of wearing it?

To describe the active process of getting dressed right now, you would use the present continuous (or present simple) tense: دارد می‌پوشد (he is putting on). The present perfect پوشیده است used in this sentence is reserved strictly for the state of already having the clothes on.

How do I connect مرد (man) and جوان (young) when reading this aloud, since there is no linking vowel written between them?

You need to use the unseen ezāfe vowel -e to link the noun to its adjective. It is pronounced mard-e javan. As a quick refresher, the ezāfe is almost never written in standard Farsi text, so you have to add it naturally in speech whenever a noun is followed by a modifier.

Does کاپشن refer to any kind of jacket, such as a formal suit jacket?

No, کاپشن specifically refers to a casual jacket, a windbreaker, or a winter coat. If the young man were wearing a formal suit jacket with his tie, the word would be کت (kot). So this sentence specifically paints a picture of someone wearing a winter or casual coat over a shirt and tie!