Think of a Space as a place where you can further organize your information, pages or tasks. Similar to departments in stores or dedicated teams in a company, you can do the same thing with your Spaces. For example, you can have a marketing or sales Space or separate your projects into each individual Spaces.
Once you create your space you can personalize it with your own custom name, icon and color. This will help you distinguish them from one another and keep your work organized.