Learn Dutch: Voor zover ik weet, is de polis geldig. - As far as I know, the policy is valid.

The phrase voor zover (as far as) is a subordinating conjunction. It introduces a sub-clause and pushes the verb to the end of that clause. Here, the clause is very short, so the verb weet comes right after the subject ik, but it is still strictly following the verb-final rule!

Why does the second half of the sentence say is de polis instead of de polis is?

This is the V2 (verb-second) rule in action. The entire first clause (Voor zover ik weet) acts as the first "block" of information in the main sentence. To keep the main verb in the second position, the verb is must come next, causing inversion with the subject de polis.

Can I drop the word voor and just say Zover ik weet?

No, you need the full phrase voor zover to mean "as far as" when introducing a clause. The word zover on its own usually means "that far" or "ready", as in the phrase Ik ben zover (I am ready).

Does polis mean the same thing as the English word "policy"?

Only when talking about insurance! A polis is an insurance policy. If you want to talk about a government rule, a political stance, or a company policy, you have to use the word beleid.