The speaker starts off by describing her own heart (and we're just guessing it's a her at this point). Through a series of similes, we learn that the speaker's heart is like a secure and singing bird, a fully-fruited apple tree, and a rainbow-colored shell in a peaceful sea. In other words, things are a-okay with her.
In the second stanza, the speaker asks for a celebratory platform (dais) to be raised. She wants it to be trimmed in fur, colored with purple, and carved with the Christian symbols of doves, pomegranates, and peacocks. While whoever's doing this work is at it, she also wants grapes and fleurs-de-lys inlaid on the piece of furniture. Why does she ask for all this preparation?
It's because the speaker's love, which she describes as her "birthday," has finally arrived—good times.