I am going to trie to explain:
I - my, mine It is my car The car is mine É o meu carro O carro é meu
You - your, yours It is your car The car is yours É o seu carro O carro é seu
He - his, him It is his car The car is him È o carro dele O carro é dele
She - her, her It is her car The car is her É o carro dela O carro é dela
It - its in Portuguese it is used for animals and not for humans
"The cat drinks its milk" and no "The cat drinks your milk"
We - our, ours It is our car The car is ours É o nosso carro O carro é nosso
They - their, theirs It is their car The car is their É o carro deles O carro é deles
Excuse my English.
I think im understanding the use & placement of articles now. From my interpreted understanding, the following:
The cat drinks it's milk. = O gato bebe o seu leite.
The cat drinks your milk. = O gato bebe seu leite.
The difference here is that the "it's" - this is the possessive, so the sentence depends on the context.
The other rule is the ommission of the noun:
Teu carro é bom, o meu não é bom. = Your car is good, mine is not good.
Because the second part of the above sentence omits the noun, you have to include the "o".
Is that correct?
Cats should not drink milk. I think it would be less harmful if they used some other beverage in the sentence, like water or something more obviously absurd such as urine or cola or gasoline, instead of reinforcing human habits that harm animals. In the same way that having the app constantly telling me that the dog eats chocolate might be harmful.