Microsoft-hosted agents

If your pipelines are in Azure Pipelines, then you’ve got a convenient option to run your jobs using a Microsoft-hosted agent. With Microsoft-hosted agents, maintenance and upgrades are taken care of for you. Each time you run a pipeline, you get a fresh virtual machine for each job in the pipeline. The virtual machine is discarded after one job (which means any change that a job makes to the virtual machine file system, such as checking out code, will be unavailable to the next job). Microsoft-hosted agents can run jobs directly on the VM or in a container.

Azure Pipelines provides a predefined agent pool named Azure Pipelines with Microsoft-hosted agents.

https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/hosted?view=azure-devops&tabs=yaml

The Link button when you click, it will provide you more insight about the agent like what are the other software which is installed on these VMs.