Cost Management requires the use of tags. Tags can be applied at the subscription level, resource group level and resource level. Tags are metadata on resources. An example is the name-value pair CostCenter. The cost center describes which department or team is responsible for a certain resource, resource group or subscription. For example: Data Integration, BI, Application Services and Infra. Knowing the resource owner means you can monitor the budget via cost management. Other examples of tags are Environment and Classification (public, sensitive, secure).
You can use up to 50 tags per resource. Tags cannot be inherited, but you can define policies to automatically add tags to resources when they exist on the resource group. See: https://docs.microsoft.com/en-us/azure/governance/policy/tutorials/govern-tags.
In the Azure Portal go to your subscription or resource group and start Cost Management. Here you can for instance filter on Tags. You can also define a Budget and assign it to a subscription or resource group.