To Injure Something
To Hurt Someone
transitive verb, ichidan verb
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb.
The kanji itself means pain, and this verb is transitive, so it means to inflict pain. In other words, it's to injure something or to hurt someone.
いためる
Since this word has okurigana (hiragana attached to the kanji) you know that it's probably going to be the kun'yomi reading. You learned that reading with the word 痛い.
ゲームのやりすぎは目を痛める。
Playing games too much will hurt your eyes.
スリッパでフルマラソンをしたら足首を痛めた。
I ran a full marathon in slippers and injured my ankles.
母は今でもそのことで心を痛めている。
That incident is still breaking mom's heart.