What is the meaning of the soliloquy in Act 3 Scene 2 lines 17-33 in Romeo and Juliet?
This speech is one in which Juliet is anxiously awaiting Romeo's arrival. It uses many figures of speech to impress on the audience the depth of her love and longing for her beloved. Overall, the effect is one of "hyperbole" or exaggeration. She personifies the night as "loving, black-brow'd night," turning the night into something human and comforting rather than a time of danger. She longs for Romeo and suggests that the joy she feels in seeing Romeo at night makes night more pleasant than day for her. She imagines that after he dies his soul might appear as stars in the heavens so beautiful that everyone would prefer them to daylight.
Her metaphor about purchasing the mansion of love but not possessing it refers to the marriage having been performed but not consummated. Just as the purchase of a house is not really complete until one has taken possession of it, marriage was not completed until it had been consummated on a wedding night. In fact, an unconsummated marriage can, according to Roman Catholic canon law, be annulled, i.e. treated as if it never actually existed:
Can. 1142 For a just cause, the Roman Pontiff can dissolve a non-consummated marriage between baptized persons or between a baptized party and a non-baptized party at the request of both parties or of one of them, even if the other party is unwilling.
Finally, she reiterates her impatience to see Romeo.
As Romeo and Juliet are married between Acts 2 and 3, Juliet anxiously awaits their wedding night in Act 3, scene 2. The lines you're referencing occur at the beginning of the scene; in them, Juliet describes the impatience she feels waiting for Romeo.
In lines 17-23, Juliet comments on Romeo's allure and says that when he's dead, and if he's cut into "little stars," he'll make the night so beautiful that no one will want it to be daytime. (Of interest is the pronoun used in line 18. In early editions of the play, the line read "when I shall die," and text with this edition often footnote that Juliet might mean that when she's dead she'll share Romeo's beauty with the world. The pronoun was changed from "I" to "he" in the Fourth Quarto.)
In the rest of the lines you list, Juliet uses figurative language to describe the impatience she feels while waiting for Romeo. She comares her impatience to the eagerness of a child who has new clothes but is not yet allowed to wear them, and she likens her new (but not yet consummated) marriage to Romeo to a "mansion of a love" which she has bought but not yet "possessed."
Finally, when Juliet sees the Nurse returning, she remarks that any news containing Romeo's name is "heavenly."
Again, these lines all show how eager Juliet is to see Romeo.