"This bunny is cute."
Translation:Tämä pupu on söpö.
Se = it. These two words have a slightly different meaning, sometimes "se" has a bit similar meaning as "the" in English since we don't have articles, so we can use that to emphasize that we are talking about a certain bunny and not just some random bunny. In my head I also imagine that "tämä" is used more often when the object is very close and visible, the same way as you'd use "this" in English in place of "the".