The time was the beginning of the morning,
And up the sun was mounting with those stars
That with him were, what time the Love Divine
At first in motion set those beauteous things...
Dante (Longfellow's translation)
"him" seems to refer to the sun. In poetry sun is masculine due to its masculine genus in Latin ( sol/ solis m). The Love Divine seems to be the Creator of the Earth and the cosmos. "what time" seems to be an adventurous substitution for "when", a literary trick, I guess, to slow down the reader's speed of reading. and forcing him to think about the sentence construction.
In plain words: It was the time when the Creator created the sun and the stars. The sun and the stars appeared in the sky, beautiful things.
Google search found the translation, a passage of Canto I
The hour was morning's prime, and on his way Aloft the sun ascended with those stars, That with him rose, when Love divine first mov'd Those its fair works:
The original, Canto I, 37-40
Temp' era dal principio del mattino,
e 'l sol montava 'n sù con quelle stelle
ch'eran con lui quando l'amor divino
mosse di prima quelle chose belle;
The time was the beginning of that (first) morning (of time),
and the Sun rose up with those stars
that were with him when the Divine Love
began to set in motion those beautiful things.
A quick spontaneous translation of mine. I permitted myself to add first and of time, to make clear that Dante speaks of the Creation. Dante's syntax is not complicated, but the translator has managed to give a somewhat difficult rendering.
Langfellow's translation was:
The time was the beginning of the morning, And up the sun was mounting with those stars That with him were, what time the Love Divine At first in motion set those beauteous things;
PS Reading the passages again I see my addition of "first" and "of time" was a bit too spontaneous. At first Dante says the sun begins to appear, it is morning while Dante is on his way to the underworld, but then he switches back in his thinking to the creation of the world when God created the sun and the stars.
PS Now, after reading a bit more about the first canto, I would translate the original a bit differently, but I think I let my first attempt stand as it is.