The smile is firmly in place as Ivan concentrates, and he tilts his head slightly while looking at the man, working this out.

Yes, he just arrived here. "Last night." It's been less than a day, still. He doesn't know what a gamekeeper is, can only assume that it is a person living in the woods, most likely in a small cottage or something, and... doing something. Maybe the person tending the woods? It seems like he should add something to the description, and decides on: "It rain." A beat. "Rains." In a month or a few days, depending on what his father decides on teaching him, he will understand tenses, but you can't start with everything at once.