That is an unusual definition of 'DevOps'
I would define DevOps as the practice of automating the provisioning of servers and other infrastructure, and the deployment of software.
Classically an organisation would have an Operations Department who's job it would be to manage the running of systems. These were the people you would call when things were down or running slow etc. But also they would be buying servers, managing the network and installing software the company had purchased.
Then you would have a Development Department who job it would be to write new software. When that software was finished it would (in theory) be handed over to 'Ops' to deploy and manage with full documentation, list of error ode and settings etc etc.
In practice the Developers would probably manually install the software the first time around. Tweaking and testing as required, then run away without giving anyone any documentation.
The separation of these two concerns can cause trouble as the Ops team don't know how to fix the software if it breaks and the Dev team (if they have a decent union) aren't on call. and in any case often the root cause will be infrastructure once the software has been illuminated from the investigation.
With the automation of infrastructure deployment and configuration Developers are able to automate much of the manual tasks which would have been required in the past. ie buying servers and plugging them in, setting up network routing and the like. thus 'DevOps'.
The hard bits of actually running datacenters can be outsourced to specialist teams and the fixing live issues is reduced to two buttons: 'scale it up' or 'roll it back'