This is the 508th most frequent Japanese word.
大切
Important; precious; valuable.
Here, 大切 is used as an adjective to describe something as 'important' or 'valuable' to the subject's emotions or preferences. It signifies emotional attachment.
家族は私にとって大切です。
Family is important to me.
Here, 大切 reflects the general or universal value or importance of a concept, in this case, health, portraying it as a fundamental or overarching necessity.
健康が大切だと感じます。
I feel that health is important.
In this sentence, 大切 is used to mean 'important' in a contextual or functional sense, indicating that the document holds crucial value for the success or execution of the project.