noun, verbal noun
So you're entering an institution. But we're not talking about any institution, we're talking specifically about hospitals. So this word means hospitalization.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
His condition deteriorated and they decided he's to be hospitalized.
While I was hospitalized, I was so bored that I couldn't stop yawning.
I'm going to be hospitalized due to breast cancer soon.