机の上に本が置いてある。

desk

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

book; volume; script; this; present; main; head; real; regular; counter for long cylindrical things; counter for films, TV shows, etc.; counter for goals, home runs, etc.; counter for telephone calls

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

to put; to place; to leave (behind); to establish (an organization, a facility, a position, etc.); to set up; to appoint (someone to a certain position); to hire; to employ; to place (one's trust, one's faith, etc); to bear (in mind etc); to put down a tool (e.g. a pen) hence stopping what one is doing with that tool; to take in (boarders, etc.); to provide lodging in one's house; to separate spatially or temporally; to do something in advance; to leave something in a certain state; to keep something in a certain state