This is the 322nd most frequent Swedish word.
barnen
"The children."
'Barnen' is used in its plural definite form to refer to 'the children', indicating a specific group known to the speaker.
Barnen leker i parken.
The children are playing in the park.
'Barnen' is used again as the definite plural form, showing possession and indicating a specific set of 'children' related to or known by the parents.
Föräldrarna hämtade barnen från skolan.
The parents picked up the children from school.
Here, 'barnen' is used to specify 'the children' in relation to a defined group, the class.