Three prizewinning Latin American films will be shown at the 11th OLA Film Festival this weekend at the Parrish Art Museum in Water Mill. Founded by Isabel Sepulveda and presented by the Organizacion Latino-Americana of Eastern Long Island, the festival will kick off tomorrow at 5:30 p.m. with “Pescador,” an Ecuadorean film, which will be followed at 7 p.m. by a performance by Mambo Loco on the museum’s terrace.