Sail
noun
The kanji and the word are exactly the same. That means they share meanings as well.
Since this word is made up of a single kanji, it probably uses the kun'yomi reading. You did not learn this reading, so here's a mnemonic to help you:
When you sail in a ship you can't forget to bring a garden hoe (ほ). If you lose your sails or your paddles, you can always use a hoe to paddle your way back. Or if you wreck on an island you can use the hoe to garden so you won't die of starvation! Hoes are very handy!
そろそろ帆を替えなくちゃいかんなあ。
Looks like you have to replace the sail soon.