This is the 12232nd most frequent Turkish word.
haftalığına
"For a week."
The word 'haftalığına' is used to indicate that the vacation is specifically for the duration of a week.
Bu hafta tatil için haftalığına Antalya'ya gidiyoruz.
This week we are going to Antalya for a week-long holiday.
Here, 'haftalığına' specifies that the trip out of town is for a single week's duration as part of the process.
Yeni işe başlamak için haftalığına şehir dışına çıktım.
I went out of town for a week to start the new job.
In this sentence, 'haftalığına' conveys that the guests' stay is limited to the duration of one week.