Book Counter
Counter For Books, Books, Counter for Volumes
counter
The kanji and the word are exactly the same. That means they share meanings as well.
さつ
The reading is the same as well. It's probably treated like on'yomi jukugo because it's attached to things (like numbers!).
市立図書館には、三万三千三百冊以上のぞう書があります。
The city library has over 33,300 volumes.
友達にもあげたかったので、その本を十冊買いました。
I wanted to give the book to my friends too, so I bought ten copies.
すみません、ちょっとお声が遠いようなのですが。日本語の教科書が何冊いるとおっしゃいましたか？
Excuse me, I’m having trouble hearing you. Did you say how many Japanese textbooks you want?