Complex sentence: High describes that Sól is one of the two children of Mundilfari, and states that the children were so beautiful they were named after the sun (Sól) and the moon (Máni).
Split into simpler sentences: High describes that Sól is one of the two children of Mundilfari. The children are described as being so beautiful they are named after the sun (Sól) and the moon (Máni).