I just stumbled upon the sentence "éistim leis an scéal". As far as I knew, "leis" meant "with him", but Duo told me I was wrong and the correct translation is just "I listen to the story". So I'm wondering, how does this verb work exactly, since an scéal doesn't seem to be a direct object? Thank you!
So, the first thing to remember is that prepositions don't map one-to-one over languages. le can mean many things, such as "with", "to", or even "for"! With éist, it means "to". So, in Irish, you don't "listen to" - you éist le.
Now, to the second part of your question. When the object of le is preceded by a definite noun, it becomes leis an/na. Yes, leis can also be le é, but it also occurs before the definite noun, which is what is happening here.
So, putting all this together:
Éistim le (I listen to)+ an scéal (the story)
Éistim leis an scéal - I listen to the story
So let's see if I understood correctly - if I were to translate "I listen to A story" it would be "Éistim le scéal"? Whereas if I have an article, then it becomes leis? I imagined the verb had to use a particular construct other than verb + subject + direct object when Duo marked my translation as incorrect, but I couldn't work it out by myself and it wasn't among the tips and notes. Thanks a lot for clarifying!
I think the way it works is that when you use a preposition + noun combo in Irish you need to use the preposition with the appropriate pronoun for the noun. So if you wanted to maybe transliterate it into English you could put it as "I listen to it—the story", but in Irish the it is just... part of what you have to do. Hopefully someone who actually knows what they're doing can give you an answer though. :P
"Le" turns into "leis" in front of the definite article, so that's that.
Can "listen" as a verb even have a direct object in either Irish or English? I'm not really sure about that... You hear something and that's a direct, accusative object... but you always listen to something and that seems more like an indirect object to me?