The project, eShopOnWeb in VB.NET (.NET Core 3.1), as its name suggests, involves converting the open-source eShopOnWeb sample ASP.NET Core 3.1 reference application to VB.NET. That .NET Foundation ...

CodeBehind Specifies the name of the compiled file that contains the class associated with the page. This attribute is not used at run time. This attribute is used for Web application projects.