To Suffer
To Struggle
intransitive verb, godan verb
You've already been introduced to the word 苦しい. That word means painful, or agonizing. So, if you turn that into a verb, you have to suffer or to struggle.
The reading comes from 苦しい, so as long as you're on top of that word, this word should be readable for you as well.
日本には長時間労働に苦しむ人が多くいます。
There are many people who suffer from long hours at work in Japan.
いじめに苦しみながら学校に行きたくないよ。
I don't want to go to school while suffering from bullying.
なぜ罪のない人が苦しんでいるのか。
Why do innocent people suffer?