There are two types of beans: bush beans and pole beans. Bush beans grow compactly to about 2 feet, and don't require a trellis. Pole beans can climb up to 10 feet, and most certainly require a trellis!
If you are short on space, trellised pole beans will produce 2-3 times the yield from the same space. However, if you want less maintenance then bush beans are the way to go.