This is the 2184th most frequent Swedish word.
national
"National" in Swedish means "national" or "related to a nation."
Here, 'nationella' is an adjective modifying 'identiteten', indicating something that pertains to or is characteristic of a nation.
Den nationella identiteten är viktig för kulturell samhörighet.
The national identity is important for cultural cohesion.
In this instance, 'Nationaldagen' is a compound noun where 'national' forms part of a term signifying a specific annual event related to the nation.
Nationaldagen firas med parader och festligheter.
The national day is celebrated with parades and festivities.
Here, 'nationella' again serves as an adjective describing 'ekonomin', denoting that the economy is considered within the scope of the nation as a whole.