She enjoyed the holidays vs. She enjoyed her holidays.

  1. She enjoyed the holidays.
  2. She enjoyed her holidays.
    Are both correct?

I think they are both correct, but #2 would usually be “holiday” unless you were talking about two different vacations. To me, #1 is talking about the typical US usage of “holidays”, probably Christmas and New Years, while #2 would refer to the UK usage as a vacation and would usually say “She enjoyed her holiday.” Probably a UK speaker would be more qualified to comment.

Luschen,
“I enjoy myself in sharing others’ happiness.”
Is it correct?

Right, in the UK, “holidays” can either refer to a holiday period, such as summer holidays or Christmas holidays, or it can refer to more than one vacation (e.g. more than one trip abroad). #1 suggests the first meaning, while #2 is somewhat ambiguous but may suggest the second. In #2, if you are talking about a single vacation (single trip abroad for example), it’s clearer to say “She enjoyed her holiday”.

No, it should be “I enjoy sharing others’ happiness.”

Or you could say “I enjoy myself when sharing others’ happiness.”