Learn Polish: Szanuję twoje decyzje, bo masz rację. - I respect your decisions because you are right.

It is in the Accusative plural. The phrase "your decisions" is the direct object of the verb szanuję (I respect). Decyzja (decision) is a feminine noun, and its plural is decyzje. The possessive pronoun "your" must match this plural non-masculine form, which is twoje.

Isn't twoje decyzje also the Nominative (subject) form? How can I tell them apart?

Yes, you are exactly right! For non-masculine-personal nouns (like feminine, neuter, and masculine animal nouns), the Accusative plural looks exactly the same as the Nominative plural. You can tell it is Accusative here because it is receiving the action of the verb szanuję, rather than doing the action.

Why does the Polish sentence say masz rację for "you are right"? Doesn't masz mean "you have"?

Yes, it does. In Polish, you do not say "you are right". Instead, you use the phrase mieć rację, which literally translates to "to have right" or "to have reason". Because racja is the direct object of having, it takes the Accusative case ending -ę, becoming rację.

How do we get the form szanuję from the dictionary word for "respect"?