Systems as in looking at how the system fits together as a whole. This can often be as complex as the details of the individual parts. How do all the parts fit together.

Example: If you are assigned to build a road you figure out the pavement so it can support the trucks driving over it. If you are assigned the system of the roads you instead look at where the trucks are going: is the route the road is on a good one (including will it hit kids on the way to school, are there good stores, will it induce demand and make things worse...), but you assume the pavement engineers will make the road strong enough.

Systems Theory is the study of complex concepts in which those concepts are broken down into a comprehensive set of smaller, interconnected components that make it easier to understand the complexity and implement. Not the best example, but you can think of it as a blueprint of sorts.

I think in this context, it is meant to describe how the underlying hardware AND software work together and to describe the potential cloud (public or private) opportunities of both.