AppExchange package install in a sandbox
Key Takeaway
The recommended practice is to install an AppExchange package first in a sandbox or a Developer Edition org, check how it behaves next to your existing setup, and only then install it in production.
An AppExchange package is a container that adds a ready-made solution, such as apps, tabs and objects, to a Salesforce org. Because a new package can interfere with what is already in your org, you test it where production users aren't affected.
Install in a nonproduction environment first
Best practice is to install a new package first in a nonproduction environment, such as a sandbox of your production org or a Developer Edition org. Experts never install in production without testing there first.
Because a sandbox is a separate environment, your production users aren't affected if something unexpected happens. Testing in a sandbox lets you confirm that the new package doesn't interfere with other installed apps or with customizations you've made. It also helps you avoid conflicts in production with things like object names.