As BurakUeda said, the 「の」 is unnecessary. Likewise, as Broccoli Forest mentioned, 「冬休み」 is the word you normally hear in Japan. So I'll talk about the meaning of 「よ」.
According to Bonjinsha's Basic Japanese-English Dictionary, 「よ」 can
- emphasize the force of one's intent, emotion, judgment, etc.
「それなりに美味しいよ」 "It's delicious for what it's worth. (so don't judge it)"
「今、冬休みだよ」 "It's winter break. (so I'm not going)"
「これはあの子に買おうと思ってるよ」 "I think I'm going to buy this for her. (so tell me that's a good idea)"
- appeal to the listener as an order, request, urging, etc.
「あした必ず来てくださいよ！」 "Be sure to come tomorrow!"
「二次会に行こうよ！」 "Let's go for round 2!"
「それはダメですよ」 "You mustn't do that."
The same meaning is echoed in Kodansha's All About Particles:
- Urges a course of action.
- Indicates a request. (Somewhat stronger than 「ね」)
- Indicates a statement of certainty.
The basic meaning of 「よ」 being, therefore, to suggest that the listener should agree with you. So you'd only really say 「冬休みだよ！」 if someone had previously said something that merits informing them that it actually is Winter Break. Usually you'll leave the 「よ」 out in this case.
And, when you mentioned 「よ」 being primarily feminine language, it's only feminine when used without 「だ」: 「あたし、試験よ」 "(No,) I'm taking a test." When used with 「だ」 it's pretty masculine.