Symbolism, Imagery, Allegory
Have you ever tried to make something that would showcase all of your talent and skill, and be really, truly beautiful? The good folks featured on Regretsy probably know a thing or two about trying (and failing) to do that, and so do the three protagonists of The Hours.
Clarissa Vaughan, Virginia Woolf, and Laura Brown each try to produce something wonderful: for Clarissa, it's a party; for Virginia, it's Mrs. Dalloway; and, for Laura, it's a cake for her husband's birthday.
The party, novel, and cake are all symbols of the women's deepest longings: Clarissa's desire to be recognized as a valued and beloved friend, Virginia's desire to finally succeed in making her writing live up to her own expectations, and Laura's desire to be brilliant and admirable, better than ordinary. As such, these items reveal the women's motivations, ambitions, and fantasies.
What's interesting is that each of these characters thinks she has failed. In Virginia's case, that is clearly untrue, though it's also true that creating Mrs. Dalloway doesn't save Virginia from her own demons. Clarissa's party fails, but she does get to meet Laura Brown, partly as a result. Laura's cake is a failure, but this failure drives her further to her new life.
Life isn't easy for these ladies, but they try to cope.