内 means inside and is a JLPT N3 kanji. It has 4 strokes and uses the entering radical (入).
Stroke order · 4 strokes
On'yomi (音読み)
ナイ、ダイ
Kun'yomi (訓読み)
うち
Radical
入 · entering
Strokes
4
How to remember 内
A person (人) has entered inside a house frame — the inside is the space within the walls. Both 内 and 中 mean 'inside', but 内 carries more of a homely, belonging feel.