件 means matter; case and is a JLPT N3 kanji. It has 6 strokes and uses the Person (side) radical (亻).
Stroke order · 6 strokes
On'yomi (音読み)
ケン
Kun'yomi (訓読み)
くだん
Radical
亻 · Person (side)
Strokes
6
How to remember 件
A person (亻) and a cow (牛) tied up in a lawsuit — an everyday 'case' from ancient courts. 件名 (subject line) in office emails — a kanji for everyday use.