This is the 11409th most frequent Russian word.
длинные
"Длинные" means "long" (plural).
The word 'длинные' is used as an adjective to describe 'волосы' (hair), indicating their length.
У девушки длинные волосы.
The girl has long hair.
Here, 'длинные' describes 'шторы' (curtains), giving information about their length.
В этой комнате очень длинные шторы.
The curtains in this room are very long.
In this case, 'длинные' is used as an adjective modifying 'карандаши' (pencils), indicating their physical characteristic of length.