Video explanation
Changing holes in a card changes the raised warp threads and woven pattern. The model also separates needles, hooks, shuttle and cloth rollers.
Holes select threads
Holes let corresponding mechanisms pass or block them, selecting warp threads through hooks and harnesses.
Warp and weft
Raised warp forms a shed for the shuttle and weft, then the reed beats it in. A sequence of cards controls successive pattern rows.
A repeatable program
Patterns encoded as hole arrangements can be stored and repeated, an idea that later influenced punched-card computing.