This is a very cheap network switch that serves as a great example of shadow IT happening in most companies. Because they were cheap and just about any computer store had them in stock, it was generally faster for an employee who had ran out of network ports to run out and grab one of these than to request proper network upgrades from the IT department. Sadly, because they are not very fast and lack features needed to prevent network disruption due to misconfigured wiring, they cause lots and lots of headaches for the IT team over time.

A good starting point to learn about physical networking would probably still be to grab a recent set of Cisco CCNA prep books and give those a read.