。
She went on a trip a few days ago.
Literal
She [topic-は] several-days before [at-に] trip [for-に] headed-out.
数日前 means 'a few days ago' — one of several vague time expressions Japanese uses where English would often be more specific. Others include 数日後 (a few days later), 数年前 (a few years ago), 先日 (the other day). 出かける is the casual, everyday verb for leaving the house, whether for errands or a vacation.