Complex sentence: Jesus is speaking to Nicodemus, a Pharisee described as "a ruler of the Jews", who says that, because of his miracles, Jesus is known "to be a teacher come from God".
Split into simpler sentences: Jesus is speaking to Nicodemus, a Pharisee who is referred to as "a ruler of the Jews". Nicodemus says that, because of his miracles, Jesus is known "to be a teacher come from God".