whats a co requisite? and what does "course credit exclusion" mean?
A corequisite is the same as a prerequisite. It means that the listed pre/corequisites must successfully be completed to take the course you are viewing.
Course credit exclusion means that the listed courses overlap in content with the course you are looking at. Because of this, you can only receive credits from one of them.
See this page for more detailed explanations.
Co-requisites essentially allow you to do two prerequisites at the same time.