To be effective, managers must act congruently. That is, managers must not only understand the concepts of good software engineering, but also practice them, which sounds easier than it is in practice. Standing in the way is a lot of emotional baggage that we all carry, the author asserts, and congruence is the way to cope with our emotional baggage.
Congruence has the sense of "fitting" -- in this case simultaneously fitting your own needs, the needs of the other people involved, and the contextual needs (in business, for example, the business needs). Examples, diagrams, and tools such as the Myers-Briggs indicator fortify the author's recommendations.