My father is so busy that he has no time to read books.

Literal

Father [topic-は] very busy [because-ので] books [object-を] read free-time [subject-が] not-exist.

暇がない ('no free time') uses がない for non-existence. ~ので connects the reason to the result. 本を読む暇 nests a relative clause: 'time for reading books.'