。
She thinks of her boss as a father figure.
Literal
She [topic-は] boss [object-を] father [like-のような] person is [quotative-と] is-thinking.
The embedded clause 父のような人だ ('a person like a father') is quoted with と and fed into 思っている ('thinks/considers'). The ~ている marks this as a sustained belief, not a passing thought. 上司 (じょうし, 'superior, boss') is the standard workplace term.