^ it goes "you are like the sun" the "who" doesn't change the sentence to "she is like the sun" meaning "you -who- are like the sun" vs "she -who- is like the sun" would be correct.
Although normally there would be a comma before the "who". Thus, "You, who are like the sun." In a lot of cases that would be a clause in a longer sentence, but if you're talking in a poetic sense it works just fine as it is. Either way, it reads pretty well.