Desayuna is the conjugation of the verb desayunar (to have breakfast) for the third person singular in the simple present. The simple present tense is used to talk about habitual actions or routines. This tense is also used to describe things that happen now or in the near future. So, we can write and translates this sentence as follows:
Marisol desayuna leche, cereales y yogurt (Marisol has breakfast milk, cereal and yogurt)
