To Fight, To Battle, To Combat
intransitive verb, godan verb
This is the verb version of the vocab word 戦い, which I'm hoping you learned earlier. The verb version of course means to fight or to battle.
たたかう
The reading comes from 戦い a word you've hopefully seen by now. Associate these words together in your mind and you'll be able to read them so long as you know the other one.
一人で戦うつもりなの?
Are you planning to fight alone?
第二次世界大戦で日本とアメリカは戦いました。
Japan and America fought in WWII.
私の兄は病気と戦っています。
My brother is fighting against an illness.