Cooking, Kitchen Work
noun, verbal noun
A cooking occurrence is just the act of cooking. It's the kitchen work. 炊事 refers to tasks involved in meal preparation as part of everyday life. It's a relatively formal word and not as commonly used as 料理, but you might see it used in lists of household chores or duties, like in a job description for a housekeeper.
すいじ
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
僕たちは、炊事をする男を雇った。
We hired a man to do kitchen work.