It's a rod brake roadster. They usually have 28 inch wheels, rod brakes, slack frames. They originated with the British, and the date I usually see cited for what we know today as the "DL-1, Model 1" or that basic pattern of bike is about 1910-1914 time range, but it's never been clear to me when exactly you would say the "modern" diamond frame rod brake roadster begins. It was certainly very early on compared to other bicycles made today. They have been made for over 100 years now.
They are still made and ridden everyday today in places like India, Pakistan, and China. They also still are used on a daily basis in places like Britain, the Netherlands, and Denmark, where there has long been a tradition with these bikes. If you were to take the basic 28 inch wheel rod brake roadster as one type of bicycle, it is probably the most-produced, most-ridden bicycle in human history.
They have the advantage of being mechanically very simple and very robust. The rod brake systems need occasional adjustment but not a whole lot in maintenance. I think of these as the Model T touring car of bicycles in that they were simple, affordable, reliable transportation for regular people in the very early part of the 20th century, onward. They can have single speed hubs, 3-speed hubs, and some custom models have even more speeds.
They're also unlike many other bicycles you find, given the wheel size, frame angles, and the way they handle. If you like long, stable bicycles, you'll probably like riding one. They are not "snappy" handling the way a 10-speed or even a regular "Sports" model would be. Globally speaking, it's probably the most significant style of bicycle made over the past 100 years. Millions and millions of people have ridden (and many still ride) these bikes as their way of getting to work, moving goods, visiting friends and family, etc. It was, and often still is, "the family car" of sorts for many people around the world.
