You should return the money.

Sono okane o kaesubekida. : You should return the money.
sono : that, the
okane : money
kaesu : return
(kaesa-nai, keshi-masu, kaesu, kaesu-toki, kaese-ba, kaese, kaesou, kaeshita)
verb+beki : should verb
Sono okane o kaesubekida. : that(the),money,return should. : You should return the money.

Kono hon o yomubekida. : You should read this book.
kono : this
hon : book
yomu : read
(yoma-nai, yomi-masu, yomu, yomu-toki, yome-ba, yome, yomou, yonda)
yomubeki : should read
Kono hon o yomubekida. : this, book, read should,: You should read this book.