Learn Polish: Wiem dokładnie, gdzie jest ten adres. - I know exactly where this address is.

The verb wiedzieć (here as wiem) means "to know a fact". You will almost always use it when your sentence continues with a question word like gdzie (where), co (what), or kiedy (when). We use znać when we know a noun, like a person, place, or object. Since this sentence says "I know where...", we must use wiem.

But isn't an address a "thing"? Could I ever say "Znam ten adres"?

Yes, absolutely! If you just want to say "I know this address" (meaning you are familiar with the address itself), you use znać + Accusative: "Znam ten adres". But the moment you add a question word to say "I know where it is", you are stating a fact about it, so the verb has to switch to wiedzieć.

Why is the word order "gdzie jest ten adres" instead of "gdzie ten adres jest"?

In English, the word order changes between a question ("Where is the address?") and a statement ("I know where the address is."). Polish doesn't do this! You usually keep the verb right after the question word, just like in a normal question. While gdzie ten adres jest wouldn't be completely wrong, gdzie jest ten adres sounds much more natural to a Polish ear.

Why is "ten adres" in the Nominative case here? Doesn't "knowing" take the Accusative?