There are two varieties of French beans: Bush beans that don't need to be trellised and climbing French beans that will need support to climb up. It just depends on what variety you have. If you're not sure and it doesn't say on the package, no big deal, just plant them and see if they start growing as a vine or a self supporting plant. If it turns out you have the vine climbing variety you could always stick in a small trellis or even a tomato cage and tie the vines to the supports as they grow.