Rosa is a very caring and loving person, and is always thinking of her loved ones. She is always happy to cook for her family, but can go overboard; if someone simply wants a snack, she will prepare an entire meal for them. When someone eats other snacks than hers, she treats it like treason and disrespect.
She is also vigilant about her loved ones' health, and will always be prepared with any old remedy she knows to make them feel better.
She cares a lot for her family. However her care for family sometimes leads her to paranoia as shown in episodes "The Spies Who Loved Me" and "Away Game". Due to her overprotectiveness she ready to spy on her grandchildren and track them in case something bad happens. She also was afraid that Ronnie and Bobby will permanently move to Arturo.
She is very superstitious as she depends on lucky talismans and assumed that Ronnie Anne was turned into a rat by black magic.
She practices old school methods of parenting her grandchildren, scaring with scary stories and beating with shoe for misbehaving. Carl is shown as target of this parenting as the least well behaving child.
She is a short, rotund Mexican American woman with tan skin, dot eyes, short black hair, rolled into a bun, and golden circular earrings. She wears a navy blue dress, with a white collar, as well as having white on the end of the sleeves, a greenish blue apron, and black shoes.
She has some similarities to Lucy. They both pop up out of nowhere, and frighten someone without them knowing of their presence, and they seem to know about spirits. The only difference is that while Lucy enjoys (the evil) spirits, Rosa prefers to keep them (the evil spirits) away.
It is revealed in "The Horror-Scope" that she met Hector when she was about Ronnie Anne's age.
"Away Game" reveals that she has heard of a woman whose kids liked her ex-husband's house so much that they moved in with him. However, it's unknown how much of this is true, since she got the information from the woman's client's cousin's friend.
"Snack Pact" reveals that she once refused to cook for Carlos for a month after he ate a churro from a newly-opened factory.