Miro is the conjugation of the verb mirar that matches the first person singular in the simple present. So we use the simple present tense when we want to talk about habitual actions or routines. Here in this sentence the subject pronoun is yo (first person singular). On the other hand, miran matches ellos/ellas/ustedes. Furthermore, mira matches usted/él/ella. Finally:
Yo miro los zapatos en la zapatería.
