What’s with it? You need to be a bit more specific what you need help with.
Also, you seem to not have read the tips and notes to the exercises, they explain most of the grammar used in the lessons. They are available in the web browser version of Duolingo (go to the https://duolingo.com website) – unfortunately they aren’t present in the mobile app. You can also read them on the duome.eu website.
I believe it to be the expected pronunciation. am generally is unstressed /əm/, so it merges with the previous vowel, so you get tha am /ham/, and that then joins with the next word starting in /m/: tha am mions /hamːins/.
So yeah… it’s not gonna be that easy to make out in natural language. Perhaps not the best sentence for listening exercise, but it’s good to know this difficulty can happen. :)
I didn't hear the am the first time either. Played it several times and found that you can hear a sort of stop in the middle of the 'a' and a bit of elongation or stickiness in the em. This is normal for humans, isn't it? Words bleed into each other 'cause we're kind of lazy when we say things over and over again, which would be the case with articles. I just played it a lot to help myself develop the ear for it.