To Smoke
To Suck, To Inhale
transitive verb, godan verb
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means suck so the verb vocab version is to suck, but it's usually used to talk about what you do to cigarettes, so a better translation I think is to smoke.
すう
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: You smoke too much, and that gives you cancer. You decide to sue (す) the cigarette makers.
これを最後に、きっぱりとタバコを吸うのを止めるつもりなんだ。
I’m going to quit smoking once and for all.