To Shoot
To Fire
godan verb
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means to attack, but 撃つ means to shoot.
This can mean to fire a weapon such as a gun or to shoot a projectile, like an arrow. It can also mean to shoot a person or animal.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you:
What are you going to shoot at? Uni (う)! Why? Because this area is overrun with those black, spiky sea urchins. You need to cull them by shooting them down.
動くな。じっとしていないと、撃つぞ！
Don’t move. Hold still or you’ll be shot!