Since this word is made up of a single kanji, it probably uses the kun'yomi reading. You haven't learned this reading yet, so here's a mnemonic to help you:
You only wear sleeves because your soap is dead (そで). If it wasn't, you would go sleeveless forever! But, your soap is dead, so you have stinky armpits, which you hide in these sleeves.
Hey, your sleeve seems dirty.
This polo shirt's sleeves are so short that people mistakenly thought it had none.
I can't tell anyone that I almost got hit by a car because I couldn't stop staring at the blood vessels that were showing on my senpai's arms from under his sleeves.