三
さん · san · JLPT N5 · noun
three
3️⃣ 三 = three strokes for three; san sounds like sun: three suns
The character is literally a tally: one stroke 一, two strokes 二, three strokes 三. Count the lines and you have the meaning. For the sound, san is close to English sun, so say it as a chant: one sun, two suns, san.
三 — three horizontal strokes 一 + 一 + 一
三 is a pictographic numeral: three stacked horizontal lines representing the number three, parallel to 一 (one) and 二 (two). The form has been stable since oracle bone script. It carries no phonetic component; the meaning 'three' is direct and visual.