This novel is full of symbols!  I will list the symbols and then explain their representations.

1.  Manderley - the grand estate owned by Max and his late wife, Rebecca.  It represents the money and prestige that the couple enjoyed.  It also represents mystery, as the truth about Rebecca's death comes to light.  By the time the events of the novel unfold, the house, to Daphne, represent a type of nightmare, of death:

The house was a sepulchre, our fear and suffering lay buried in the ruins. There would be no resurrection. (Chapter 1)

2.  Jasper - Max's dog.  At one point the narrator, whom many call Daphne, feels as if the dog represents her own relationship with Max.  When she sees him absently patting Jasper's head, she notes that her relationship with Max is quite similar:

He pats me now and again, when he remembers, and I'm pleased, I get closer to him for a moment. He likes me in the way I like Jasper." (Chapter 9).

3.  Rebecca - Max's dead former wife.  Even dead, Rebecca represents an aspiraton that Daphne can never achieve.  She will never be as beautiful, as poised or as respected.  Rebecca is an unachievalbe goal.

4. The broken cupid - a simple china figurine that Daphne breaks and hides in a drawer.   This cupid represents Daphne's ineptitude at fitting in to the lifestyle once belonging to Rebecca.  Daphne cannot undertake to maintain the household in a way that Rebecca could and is constantly reminded of this by the cruel Mrs. Danvers.

5.  The fancy ball gown - a copy of the gown that Rebecca wore on her last night alive.  This gown is given to Daphne to wear as a cruel  joke, causing Max and the other guest to respond with anger and embarrassment.  The gown symbolizes the love and popularity others had for Rebecca.  Daphne is very out of place wearing it.