To teach or instruct someone (knowledge, skills); to give instruction.
先生が学生に日本語の文法を教えている。
The teacher is teaching Japanese grammar to the students.
弟にピアノの弾き方を教えている。
I'm teaching my younger brother how to play the piano.
大学で物理を教えるのは彼の仕事だ。
His job is to teach physics at the university.
To tell or inform someone (facts, information, directions); to show.
住所を教えてください。
Please tell me your address.
道に迷ったので、駅までの行き方を教えてもらった。
I got lost, so someone showed me how to get to the station.
本当のことを彼に教えたほうがいい。
It's better to tell him the truth.
To preach or expound teachings (religious, moral, or doctrinal); to propagate beliefs.
僧侶は寺で仏法を教えている。
The monk teaches Buddhist doctrine at the temple.
彼は若者たちに生き方について教えを説いた。
He preached teachings about how to live to the young people.