、。
Reading books is a habit of mine.
Literal
Book [object-を] read [nominalizer-の]-[topic-は], my [attributive-の] habit [is-である].
The の-nominalized verb phrase 本を読むの ('the act of reading books') is the topic, with the noun 習慣 ('habit, custom') and the formal copula である as the predicate. The formal/written register suits an essay or self-description. The 私の possessive phrase specifies whose habit. Notice how two different uses of の appear in one sentence: the nominalizer (読むの) and the possessive (私の).