This course is about the fundamental capabilities and limitations of computers. These topics form the core of computer science. 
It is about mathematical properties of computer hardware and software.
This theory is very much relevant to practice, for example, in the design of new programming languages, compilers, string searching, pattern matching, computer security, artificial intelligence, etc., etc.
This course helps you to learn problem solving skills. Theory teaches you how to think, prove, argue, solve problems, express, and abstract.