Programming statements that can be easily understood by the author or another programmer. Some languages are inherently more self documenting than others. For example, to the novice, COBOL provides more self-documenting code than C.

It's Very Subjective
However, what one programmer thinks is self documenting may truly be indecipherable to another. For example, today's operating systems offer hundreds of programming interfaces (APIs) that the application may call. If programmers are familiar with those calls, they may feel that English commentary is unnecessary, because the API uses a logical name and is well documented by the OS vendor. However, in order to understand the code, a third party not familiar with the calls has to keep flipping back and forth from the application source code to the OS documentation, presuming it is readily available in the first place. A well-written line of English for each of these calls would be far more helpful.