Translation:I think I am going to take a vacation this week.
The translations seem to have a constant problem with not recognizing "I think that" as the equivalent to "I think".
Actually, in correct standard English grammar, that second clause should be introduced by "that", thus leaving it out is in error.
Only in a very prescriptivist grammar is the "that" necessary. If a grammar rule disagrees with a significant number of native speakers, perhaps the rule should be questioned.
I'm not a native speaker, but I don't think you can take holidays from work, only vacations.
In British English, the word "vacation" is rarely used - "holiday" or "holidays" are much more frequent.
It is allowed as an answer now. As Fintan says, it is used all the time in the UK.
I guess that should be correct, unless duo has holiday programmed in the singular form as 'feriado'.