Three Books
Three Volumes
Three books equals three books.
さんさつ
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
この図書館では、本は三冊まで借りれます。
In this library, you can borrow up to three books.
コウイチは、ヌード写真集を三冊だけ発行しました。
Koichi released only three volumes of his nude photography book.
「今日は日本の小説を三冊読むぞ！」「はは。出来るもんならやってみな。」
"I’m gonna read three Japanese novels today!" "Haha. You wish."