器 means vessel; capacity, ability and is a JLPT N1 kanji. It has 15 strokes and uses the mouth radical (口).
Stroke order · 15 strokes
On'yomi (音読み)
キ
Kun'yomi (訓読み)
うつわ
Radical
口 · mouth
Strokes
15
How to remember 器
Four mouths (口口口口) with a dog (大) in the middle — a house full of dishes! 器用 means skillful hands; 楽器 means musical instrument; 器 also means capacity of mind.