。
She is hoping he'll show up Saturday afternoon.
Literal
She [topic-は] [he [subject-が] Saturday's afternoon figure [object-を] show [nominalizer-の]] [object-を] is-hoping.
姿を見せる ('to show one's figure') is an idiom for 'show up, appear' — slightly more dignified than just 来る ('come'). The whole proposition is nominalized with の and marked with を as the object of 期待する ('hope, expect'). 期待 carries a stronger sense of looking forward to something than just hoping.