As you can see in the page, it's 2 episodes OVA, but in truth it's a on movie compiling it having like a more or less 1hr duration. The plot is literally like any OVA, so you can watch it without being preoccupied if you watch the whole series or not, though you need to at least know the main characters, Yun Yun and Wiz I will resume a like in just some words but not literally, the imagination is for you guys. The first is a "beach" episode and the second one is like the battle of two "protagonist's" group If you watched at least any ofthe konosuba you know that you're going to laugh a lot

And then it's a spoiler but not a spoiler at the same time since it's just a notice that they give to us, and it's about Konosuba getting a new season!!!

Btw, this movie makes me like Wiz more than the others now, if you know what I mean after watching it lol