Within your template, the dependsOn element enables you to define one resource as a dependent on one or more resources. Its value can be a comma- separated list of resource names.
Box 1: 'Microsoft.Network/networkInterfaces'
This resource is a virtual machine. It depends on two other resources:
Microsoft.Storage/storageAccounts
Microsoft.Network/networkInterfaces
Box 2: 'Microsoft.Network/virtualNetworks/'
The dependsOn element enables you to define one resource as a dependent on one or more resources. The resource depends on two other resources:
Microsoft.Network/publicIPAddresses
Microsoft.Network/virtualNetworks
Reference:
https://docs.microsoft.com/en-us/azure/azure-resource-manager/resource-manager-tutorial-create-templates-with-dependent-resources