This is a distich from Daniël Heinsius' emblem collection entitled Quaeris quid sit amor? (sometimes also titled: Emblemata amatoria) published c. 1601. You can find the book online at the Emblem Project Utrecht.
Inter Omnes
Obtenebrat stellas, Phoebe: tu sola puellas:
Pulchrae essent aliae, tu nisi, pulchra, fores.
The vocabulary is keyed to the DCC Latin Vocabulary list. There are only two words in this poem that are not on the DCC list:
obtenebrō, -āre - make dark, darken
Phoebus, m. - Phoebus Apollo, sun god, sun
alius -a -um: other, another; alias: at another time
inter: between, among; during (+ acc.)
nisi/nī: if not, unless
omnis -e: all, every, as a whole
puella -ae f.: girl; girl-friend
pulcher -chra -chrum: beautiful
sōlus -a -um: only, alone; sōlum (adv.), only, merely
stella -ae f.: star
sum, esse, fuī: be, exist
tū tuī tibi tē: you (sing.)