How to plot a bar plot with bars and labels between tick marks

I had this quesition when preparing my manuscript and a quick search brings me to this stackoverflow question by Johanna. I find the answer by Henrick to be highly effective, but can be further elaborated so that readers can be clearer about the functions of each line. Thus, I will base my post largely on Henrick’s answer but at the same time add my explanation to the rationale behind the lines.