Sandbox refers to an isolated testing environment that enables developers to run applications without affecting other applications that have critical devices or users connected. 

Use sandboxes to test new applications with the confidence that they will not impact others.

To create a sandbox, just add a new profile, and use it for your tests. Make sure that all critical applications are running in another profile.

For example, if any of your tests demand higher level of services (limits) and lock that profile, it will not block the applications running in other profiles.

Increase team collaboration and add more developers in your sandbox. For this, you just need to share your profile with others.