Translation:I really enjoyed my winter vacation.
This has been bothering me too. It seems "I enjoyed a lot of my winter vacation" is actually the correct translation of this sentence despite Duolingo not accepting it. "Realmente disfruté mis vacaciones de invierno" is how you say I really enjoyed my winter vacation.
Hopefully some better speakers can chime in here.
No, that doesn't really add up. If you want to apply mucho as an adjective to the noun "vacaciones", it must agree in gender and number: "Disfruté muchas de mis vacaciones de invierno." (Yes, and you'd need de here since you're not talking about multiple vacations, but many parts of one vacation.)
In the original sentence, mucho is an adverb modifying the verb disfrutar.
Question - is "I enjoyed my winter vacation a lot" not acceptable here?
Lol Of course, English speakers realize (in spite of the misprint) Holiday is but a derivation of Holy Day. (That was the only time when the king/queen and church granted time away from toil, for rest and festivities.)
In North American English, a Holiday has been expanded and come to be expressed as a Vacation. (Time to get out of Dodge/ Vacate the premises)
Meanwhile my lord. I beseech thee, that thou wouldst grant me leave for Holyday. Pretty please? ;)