。
She goes to the beauty salon at least once a week.
Literal
She [topic-は] at-least week one-time beauty-salon [to-へ] goes.
少なくとも (すくなくとも, 'at least') sets a minimum frequency. 週一回 (しゅういっかい, 'once per week') is a compact time expression: 週 ('week') + 一回 ('one time'). 美容院 (びよういん, 'beauty salon, hairdresser') is distinct from 床屋 (とこや, 'barbershop') — 美容院 traditionally serves women while 床屋 serves men, though the distinction is blurring.