"They are closing the store."
Translation:One zamykają sklep.
Are they slimply closing the store because they are going home after work? or can it also be because they won't be opening it anymore?
It could be both. But for the later you can also use "likwidują".
This can also mean they are locking the doors to the shop.
How am I meant to mind read that duo is going to use the masculine form of they
You can't, and in 99% of the sentences both are equally correct. In fact, I see the feminine form right now at the top.
So, I don't yet understand why I can't/shouldn't use "ten" sklep in my answer
'ten sklep' is accepted, it should have worked.
It wasn't technically in the English sentence, and it's less probable here than in many other sentences, but you can interpret 'the shop' as 'this shop'.