It was an ethernet that was developed in the 1970s that improved the ability to send the information over the network. It is the most widely used method to connect the computers in a LAN or the local area network, ever since 1980 when it was first introduced for commercial use. And it is being used in bulk even today.
It’s hz and bandwidth, 5ghz is better then a 2.5ghz but the wavelength is more condensed so it won’t travel so far so the 5ghz will be faster but the 2.5ghz will go further.