The object of the verb enjoy omitted
I enjoyed during the holidays.
I enjoyed myself during the holidays. Or: I enjoyed my holidays.
We say I had a good time, as this is an idiomatic expression, but we can’t say I enjoyed my time. We must specify. I enjoyed my time in Greece. Don’t follow the verb enjoy by a preposition. It must always have an object, which may either be a reflexive pronoun or a noun.