What it means
てあげる attaches to the te-form of a verb to show that the subject does something for another person as a favor or helpful action. The recipient is commonly marked with に. The subject is usually the speaker or someone whose action the speaker is describing, and the action is understood to benefit the recipient.
Usage note
てあげる can sound patronizing if you use it when offering a favor to someone of higher status, because it can emphasize that you are doing something for that person. Use it carefully in formal situations. The polite counterpart is てあげます.
How to use it
私は弟に漢字を教えてあげます。
I will teach my younger brother kanji.
私は弟に漢字を教えてあげる。
I will teach my younger brother kanji.
Example sentences
妹に自転車の乗り方を教えてあげました。
I taught my younger sister how to ride a bicycle.
雨の日、友達に傘を貸してあげました。
On a rainy day, I lent my umbrella to a friend.
祖父に庭の木の枝を切ってあげました。
I cut the branches of the tree in the garden for my grandfather.