Remember that a symbol is something that stands literally for itself but also stands for something metaphorically or symbolicially. Thus, in our culture, a dove is a picture of a dove but has come to be associated with peace. In this fascinating novel, then, there are clearly a number of symbols. I will talk about the biggest symbol in the novel, which is the Shadow that Ged unleashes and then strives against, but you can then go on to use my analysis to talk about other symbols you can detect. Just to give you some idea, you might want to think about naming and staves act as symbols.
I will start by considering the symbol of the shadow by talking about what is said of the shadow at the end of the novel:
And he began to see the truth, that Ged had neither lost nor won but, naming the shadow of his death with his own name, had made himself whole: a man: who, knowing his whole true self, cannot be used or possessed by any power other than himself, and whose life therefore is lived for life's sake an dnever in the service of ruin, or pain, or hated, or the dark.
This quote is highly significant in my mind because it reveals that the Shadow is actually a symbol of incompleteness or danger. Without it, Ged as a character is left open to be consumed and dominated by other forces. Yet with it, having joined with it and being one with it, Ged is much more stronger. Having joined with his Shadow Ged has been given the gift of self-knowledge. We are never directly told the true meaning of the Shadow, but I wonder whether it symbolises our capacity to perpetrate evil - our dark side. Having joined with his Shadow, Ged has been forced to accept and come to terms with his own capacity to cause evil and destruction, and having accepted this has become much stronger as a result.
Hope that helps - now good luck with identifying other symbols and analysing them!