This is the 13563rd most frequent Russian word.
национальное
"National."
In this sentence, 'национальное' refers to something that belongs to or is characteristic of a nation, specifically addressing cultural heritage.
Национальное достояние России — это её культура.
The national heritage of Russia is its culture.
Here, 'национальное' is used to refer to unity among people sharing a common national identity.
Эта партия пропагандирует национальное единство.
This party promotes national unity.
In this instance, 'национальное' describes education that is intended to maintain and reflect the values and traditions of a nation.