App is a collection of DocTypes and Reports, Apps can be created by Users with System Administrator Role. Multiple apps can be created in a Workspace, you can create separate apps depending on your business operations or purpose. e.g. CRM, Purchase, Accounting, Order Management, etc.
Navigate to Main Menu (Left-side panel), Click on "Create New App" option
Enter "App Name" in Pop-up dialogue box, Click on "Create",
Your created app will be available in Main Menu Panel.