"Holiday" typically refers to specific religious or national days of recognition that may or may not result in days off from work or school. In the US we have holidays like Christmas, Martin Luther King day, Thanksgiving and Independence Day. These are days that have roots in religion, important times in our country's history, or notable people in our history. "Vacation" can be a couple things: One, it could be what you DO during a holiday such as Christmas. Students often will get a week or so off around this particular holiday and will "go on vacation" which implies they traveled somewhere during the holiday. Also vacation could just be scheduled time off (not due to any sort of holiday) which I think is the context you are referring to in your question. Students typically have an extended time off during the summer which is referred to as "summer vacation". So if I was to take a guess, I'd say that you're trying to say "I can't wait for summer vacation" Side note: More and more people have begun to use the word "holidays" (plural) or the "holiday season" as the period of time between Thanksgiving (late November) through the New Year. This is generally thought of as a way to be more inclusive to other religions besides Christianity who may celebrate holidays during this time such as Hanukkah. Or even simply for people who don't relate to any particular religion but enjoy spending time with their friends and family during this part of the year. In this instance you could say "I can't wait for the holidays/holiday season"