At first hearing sounds like they're shopping for stocks :D
What case is used in this sentence? Is this type of sentence structure "minä olen.... doing something" correct?
It's literally "I'm at purchases", but it means to be shopping
https://en.m.wiktionary.org/wiki/ostoksilla It's adessive plural of "ostos".
Here's more about "ostos": https://en.m.wiktionary.org/wiki/ostos#Finnish
Thank you. :)
Just found a site that explain the pattern [ olla + x:lla ].