Both are nice, as you can see in the first line of the second paragraph (Rafael es simpático) and the first line of the third sentence (Yesica es simpática). What they do not have in common is their hair color, Rafael is dark haired (moreno) and Yesica is blonde (rubia). Both live in New Jersey, (vive en Nueva Jersey), but Rafael is African, Mexican, and American (Es africano, mexicono y es africano, mexicano, y estadounidense) whereas Yesica is Columbian (Es de Columbia).
I'm sure this isn't everything, but I hope it helps!
un - masculine singular
una -feminine singular
unos - masculine plural
unas - feminine plural
UN lápiz - a pencil
UNAS tareas - some homework
UNOS borradores - some erasers
UNAS mochilas - some backpacks
UNOS libros - some books
UNA calculadora - a calculator
UNOS papeles - some papers
UN examen - a test
Many times we can find the right article by paying attention to the noun ending:
unAS tareAS
unOS librOS
