"He owns dogs" incorrect? Or "keeps"? Please reconsider.
Just translate literally. Of course it can mean the same, but owning is 'bezitten' and keeping is 'houden'. Stick to the literal translations, that's easiest.
That is incorrect, because he HAS dogs. This does not mean he owns then ((he could be walking them for a friend)) or that he keeps them ((he could let go of the leashes)).
"He owns dogs" is actually a possibility depending on the circumstances. Keeps, on the other hand is too far off.
So to form a plural in Dutch, you simply add "en" to the end of the word, like the s at the end of most English plurals?
That's probably the most common way, but it's not the only one. You can find a lot of information about how plural nouns are formed here: Grammar: Dutch plural nouns
Honden!! En geen kannen!!
They said in the translation "have" from "heeft". Why is "He have dogs" not good then? I'm dutch, but this doesn't makes sense...
Third person singular in English is - He/She/It has.
She He It 3rd Person Singular may conjugate with Have by including an Auxiliary Verb [ which provides the 3rd Person Singular Conjugation ]:
¿Does he have dogs? •
Yes, he does have dogs.
This is not hard but if you try