The word "deceit" refers to an erroneous and dishonest procedure. A person who hides something from someone or who disobeys the order of someone is practicing a wrong and dishonest procedure, that is, is practicing "deceit".
In that excerpt, Nora is hiding the macaroons she was eating from Torvald because he forbade her to eat them. Nora is hiding and practicing a dishonest act, disobedience. With this, we can conclude that the macaroons symbolize "deceit" in relation to Nora's relationship with Torvald
