A property is a set of Google Analytics reports and data associated with one or more websites and/or apps. If data should generally be analyzed together (product line, brand, application), data should be in one property. Learn more about account structure
The reports and interface vary depending on what kind of property you are using. For example, a Universal Analytics property has different reports from a Google Analytics 4 property.
You can create a Google Analytics 4 property and/or a Universal Analytics property. Because Google Analytics 4 is the future of Google Analytics, we recommend creating at least a Google Analytics 4 property. Creating both allows you to view both Universal Analytics reports and Google Analytics 4 reports. You can switch back and forth between the two different kinds of reports via the property selector or Admin screen.