What can we imagine about how the male character looks when there is no physical description of him?
I tend to agree with the description of the way to imagine the narrator as it is described by the enotes link below. One of my favorite parts about good short stories, like this one and others by Kazakov is the way that they leave certain things out for the reader to imagine or think of.
In this way, we learn of the young man's determination, his decision to leave a previous life behind him and find the special communion with nature and the power of it in this particular place. He demonstrates this in the very careful way he shows things to the girl, in his great desire to have her feel some of the things he does and in the end to stay with him.
Through these actions we learn that he is determined and strong and also very thoughtful. He is obviously a deep thinker, but we don't have to read his every thought to learn this. Kazakov hints at this very effectively and then allows the reader to draw their own conclusions.