This is the 908th most frequent Arabic word.
لفترة
"For a while" or "for a period."
Here, 'لفترة' indicates a time duration the action of going to the library lasted.
ذهبت إلى المكتبة لفترة قصيرة.
I went to the library for a short period.
In this sentence, 'لفترة' describes the extent of time I plan to stay.
سأبقى هنا لفترة طويلة.
I will stay here for a long period.
The usage of 'لفترة' here expresses a temporary state or feeling that was experienced.