A semantic desktop is like having a magic genie who can remember everything you say and do on your computer. It can understand the meaning and relationship between all the things you save, like files, emails, and even pictures.
For example, if you save a recipe on your computer, the semantic desktop would not just see it as text on a page, it would understand that it's a recipe for food and might even be able to tell which ingredients you need. This means that when you want to find that recipe again, you can search for it by the ingredients you have on hand, instead of just the name of the recipe.
The semantic desktop can also help you by organizing your files in a way that makes sense to you. It might group all your recipes together, even if they are saved in different places on your computer.
Essentially, the semantic desktop is like having your own super smart personal assistant who can help you find and organize everything on your computer in a way that is easy and makes sense to you.