noun, な adjective
When something has a heavy need, you know that that thing is essential. It is important.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
The important thing is to be healthy.
When I was in elementary school, I thought it was important to make friends at school.
It was an important announcement for the people.