A speaker hears the stars calling their name and answers by calling each star in turn, one by one across the sky. It's a small, intimate exchange: the stars speak first, and the speaker doesn't just listen but replies in kind, as if the two sides are old acquaintances.
The last two lines add a note of effort and longing. The speaker is "working hard" so that the "blazing glory of day" will no longer stop them. Daylight, usually welcomed, becomes an obstacle, because it hides the stars and keeps the speaker from the conversation they care about most. The speaker seems to want to reach a point where nothing, not even the brightest sun, can cut that connection.
The mood is quiet, devoted, and a little wistful. There's wonder in it, but also determination. The parentheses around the whole poem make it feel like something whispered or kept private, a secret the speaker is sharing with us.