necessities; necessary things
Refers to things that are needed or essential, often in a practical or everyday context.
Before the trip, I listed the necessities.
Prepare the necessities in case of an emergency.
必要 is an adjective/noun meaning 'necessary' or 'need'. 必要事 is a noun meaning 'necessary things' or 'necessities', emphasizing the items or matters themselves.
Compound of 必要 (hitsuyō, 'necessary') + 事 (ji, 'thing, matter'). The exact historical derivation is uncertain, but the word is transparently formed from these two elements.