Learn Croatian: Ovaj čovjek je tamo.

Ovaj is a demonstrative pronoun meaning 'this', and it must match the gender of the noun it points to. Because čovjek (man) is a masculine noun, we use the masculine form ovaj. If we were pointing to a feminine noun, we would use ova, and for a neuter noun, ovo.

Could we put je at the end and say Ovaj čovjek tamo je?

No, because je (is) is an enclitic. An enclitic is a 'weak' word that sounds unnatural at the very beginning or the very end of a sentence. It prefers to sit in the second position. Here, the whole phrase Ovaj čovjek acts as the first block of information, so je safely tucks in right after it.

Does čovjek only mean 'man', or can it mean 'person'?

Čovjek can mean either 'man' or 'human/person' depending on the context. In this sentence, because we are pointing out a specific male person using ovaj, translating it as 'man' makes the most sense.

How do I know when to use tamo instead of other words for 'there'?

Tamo specifically means 'over there', implying that the person or thing is far away from both you (the speaker) and the person you are talking to. If the man was standing right next to the person you were talking to, you would use tu instead.