Perché ci sono queste sacche, cosa si deve fare??

Hi there, the little bags are pre flowers, these are what develop into buds, sometimes the plant doesn't always blow them up though, tis normal so I would not worry and remove them, the ones that don't develop generally fall off later anyhow.

The best thing to do is study plant biology. Then you can identify the different parts of the plant, and have basic information on what is normal, what it should look like, or if something is abnormal. If you need help finding resources, there are plenty of books and online information sites that discuss plant biology with a focus on cannabis biology.