You need to mount an Azure storage account (block blob storage container or Azure files storage) to an Azure App Service instance. Most often this is needed for allocating some extra storage space to be exposed natively to your App Service, instead of using the native “c/home/site/wwwroot” file system quota. This article provides guidance on how to mount Azure Storage as a local share in Azure App Service.
Provide all the Azure storage mount configuration and click OK to create the mount.
Mounting an Azure storage account to Azure App Service is currently (as of November 2022) an Azure preview service whose functionality is described at: https://azure.microsoft.com/en-us/updates/public-preview-azure-storage-as-share-in-windows-code-in-app-service/.
A detailed step-by-step guide is also provided by Microsoft at: https://learn.microsoft.com/en-us/azure/app-service/configure-connect-to-azure-storage?tabs=portal&pivots=code-windows.