"I love them a lot."
Translation:Eu os amo muito.
I know Duolingo is going out of its way to avoid discussing grammar but I don't think that's the right way in this case. I would never have guessed that ‘lhe’ is only dative had I not looked it up.
For reference, here's a table:
case [I] [you] [he] [she] [we] [you p] [they m/f] [reflexive]
nom. eu tu ele ela nós vós eles elas
dat. me te lhe lhe nos vos lhes lhes se
acc. me te o¹ a¹ nos vos os¹ as¹ se
prep. mim ti si
com: comigo contigo conosco convosco consigo
Omitted prepositionals take the nominative.
¹ After a verb: ‘-o’ becomes ‘-no’ after a nasal vowel. With X a consonant, ‘X-o’ becomes ‘-lo’; accent doesn't shift and must be marked if necessary.
Because "lhes" indicates an indirect object, while "os/as/los/las" indicate directs objects. And the verb "amar" (to love) is like: "who plays, plays something" (asks for a direct object) and not "he passed to us - indirect object - the ball". It's like: "you love someone" and then you have to use "eu os amo" or even "eu amo eles".