Today I read the detail description of didregress from STATA. from page 6 and 7, there is a point that I have not yet been cleared

The setting is on page 6

A health provider is interested in studying the effect of a new hospital admissions procedure on the satisfaction of patients. The provider has monthly data on patients from January to July. The new admissions procedure was implemented in April by hospitals that were under new management. Of the 46 hospitals in the study, 18 implemented the new procedure.
And the results of the regression on page 7
Array


I do not understand the part highlighted above. I am still consufed about the number 1 1 4 4 at the second segment of the first table above. I try to read the example many times but still get lost in this case.