I don’t know what pretérito is pls help

Does anyone know what my spanish teacher means by this? i need to use plural forms of the verb ser. and she asked me to use a couple of adjectives to describe the boys collectively and then the girls collectively?

What would you purchase at a quiosco? a. fresas b. patatas c. aspirinas d. periódicos

—¿ es tu celebración favorita? —mi celebración favorita es el cumpleaños de mis hijos.