Phrase synonymous to "a general understanding"?

Solution 1:

You can use the phrase superficial understanding, or simply, general insight into a particular subject.

You don't really have to qualify understanding as "general". If you wrote

Writes clean and concise code that reflects an understanding of the codebase and its external modules.

then this would have the exact meaning you want.

e: Please remember that if you think this answer is wrong, you should consider leaving a comment explaining why. :)