Floor-standing speakers are generally one meter or taller and relatively narrow. That's why you'll often hear them referred to as "tower speakers".
They have larger internal air space than bookshelf speakers do (as some audio engineers would say, there's no replacement for displacement), and frequently employ multiple woofers. A tower speaker often offers deeper bass and fuller sound than their smaller speaker counterparts.
If you have a large room, tower speakers are the ultimate way to go for creating a dynamic and realistic listening experience.