"Jessica says that she's calling (him/her)."
Let's break it down:
* Dice: Means "says" in the third person singular (she/he says).
* La Jessica: Means "Jessica" (the feminine article "la" is used before proper nouns in Spanish).
* Que: This is a conjunction meaning "that."
* Le llama: Means "she/he calls (him/her)." "Le" is an indirect object pronoun meaning "to him/her," and "llama" is the verb "to call" in the third person singular present tense.
This phrase implies that Jessica is calling someone, but it doesn't specify who that person is.