A solution package is a bundle of components, such as Power Apps, Power Automate, and Microsoft Dataverse, that can be promoted from one environment to another. To create the solution package for promotion in a company that is implementing Power Apps and Power Automate, the package should be created in the Microsoft Power Platform admin center.
In the Power Platform admin center, you can create a solution package that includes the necessary components and export it as a .zip file. This file can then be imported into the desired environment, such as the user acceptance test environment, to promote the components.
Reference:
https://docs.microsoft.com/en-us/power-platform/admin/solutions/create-solution
https://docs.microsoft.com/en-us/power-platform/admin/solutions/import-solution
https://docs.microsoft.com/en-us/power-platform/admin/solutions/export-solution