Discuss the meaning of the sonnet in Act I, sc. 5 of Romeo and Juliet.

I am going to presume that you are speaking of the moment
that Romeo sees Juliet and launches into how she looks.  If not, you might need to
repost the question.  I could only find this as the closest thing to a sonnet in this
scene.

The basic idea behind his speech/ sonnet to Juliet's
beauty is that Romeo's self- torturing and pining for Rosaline is now a thing of the
past.  The sight of Juliet now has become his focus.  He is naturally taken back by his
beauty and the opening lines of the sonnet reflect how he sees her from a physical point
of view.  The comparisons of a "jewel  in an Ethiop's ear" and "Beauty too rich for use"
should give some indication that he finds her physically beautiful.  It should also help
to reveal something about his character as being impulsive, as the previous four scenes
have revealed him to be miserable about Rosaline and then once he sees the attractive
Juliet, all pain disappears.  The ending of the sonnet speaks of how he has become a
pawn for this sense of "true beauty." The speech/ sonnet ends with the idea that Juliet
is beautiful and Romeo has fallen in love with her.

If the
reader is to take anything away from this, it would be that Juliet is naturally
beautiful.  The speech also reflects that Romeo sees "love" and "infatuation" as one in
the same.  The fact that he is able to immediately fall in love with Juliet is a
reflection of how he sees her as beautiful and then is attracted to this.  This
naturally begs the question of what would have happened had Juliet not been attractive? 
Would Romeo have fallen in love for her and been able to see this "torch that teaches
other torches to burn bright" in the same light?  One other implication that comes out
of this scene.  There is a heck of a lot of objectification that goes on in this
speech.  True love, it seems involves seeing someone and immediately relegating them
into the category of things.  The speech expresses this with moving Juliet into the
realm of torches, jewels, snowy doves, and the like.  There is little discussion of
Juliet's emotional sense of being as well as whether or not he will be found in the same
light by her as he finds her.  I think that this brings out a great deal about Romeo's
character and what passed for love in the context of the play.  This is not to say that
he did not love her.  He does die for her, or for some semblance of her.  Yet, I think
that it is important to note in the sonnet how Romeo initially conceives of his
affections for Juliet.