How can I vote on 600 questions but only 25% of them are on questions? Did it originally mean "600 posts"?
The description is accurate:
These two things are not mutually exclusive. Note "total votes" is total votes, which is the total of all your votes, not just questions.
If you cast 3000 votes and 600 of those were on questions, you would not qualify, as only 20% of your total votes are on questions. On the other hand if you cast 700 votes and 600 of those were on questions, you would qualify.
You are not the first to be confused by this, however. Related reading:
Vote on 600 questions and 25% or more of total votes are on questions
Literally! At least 25 percent of your total votes were cast on questions. I think you read past the "total votes" part hence the confusion. 25 percent of votes on posts, not just the posts. This is of course a two-piece condition:
Vote on 600 questions
25 percent of all your votes were cast on questions
Twp different conditions, under the same badge. You should consider that in your first question:
How can I vote on 600 questions but only 25% of them are on questions?
"[T]hem" would represent the votes you casted.