Is job experience more valuable than taking more courses?
If the "job experience provider" would write a good recommendation for you afterwards (surely you must also deserve it), this may matter more. 

Unless you skip some very basic course that your future company sees as very useful for your work. For example, if the future company focuses on C++ development, a course with good marks in C++ programming may matter more than work in some company that required HTML/CSS only. 

I would say, take that job but think well which course deserves dropping most of all.