The course covers signals and systems. We talk about ways of modeling physical and electrical systems (or any other system really) as combinations of smaller components, and use the characterizations we derive of the smaller systems to characterize behavior of the larger ones. We use tools like the fourier transform to simplify the analysis.
When I took it ~25 years ago it was called Intro to Systems Engineering, and covered the foundational principles of control systems design and analysis of linear dynamic systems. A lot of Laplace transforms, first- and second-order differential equations, relationships between time-domain and frequency-domain behavior, etc.
The things I learned in the basic engineering course that really stuck with me were convolution, the sampling theorem, and the Fourier transform. That knowledge has been invaluable.
This wikibook seems to cover the same topics: https://en.wikibooks.org/wiki/Signals_and_Systems