She got the job thanks to her youth and enthusiasm.
Literal
She [topic-は] youth [and-と] enthusiasm [thanks to-のおかげで] job [object-を] got.
若さと熱心さ pairs two ~さ nominalizations: 若さ (youth, from 若い) and 熱心さ (enthusiasm, from 熱心). のおかげで attributes the positive outcome — getting the job — to these two qualities. 仕事を得る (to get a job) uses the slightly formal 得る rather than the casual もらう.