DevOps is a small piece of the wider Agile framework pie but in the Microsoft technology stack it's the arguably the most relevant to Azure services. DevOps is a little bit strange to those of us with Infra and Ops backgrounds so I've collected the key phrases and things you'll hear when talking about Azure DevOps (and DevOps in general).
My goal was to try and show the relationships between the most important concepts in one image. The result is not perfect and it certainly doesn't cover this huge topic in one fell swoop, but it's a really good starting point to help you understand how it's a cultural shift, a way of thinking, hence the first priority is 'people'.

The first part is about a change in the way people interact and collaborate towards mutual goals, beyond traditionally siloed boundaries. The idea is to foster a CI/CD culture to continuously refine the operating model and delivery output of the organisation.
Successful adoption of such a radical culture change is built on processes, or sometimes lack of! Here I've placed some familiar solutions to illustrate how they contribute towards the bigger picture.
The processes require the right tools to support CI/CD value. IaC is popular trend, typically this is achieved with Terraform or more recently, Azure Bicep, both of which allow you to deploy resources in the cloud via code.