In the past, Wi-Fi versions were identified by a letter or a pair of letters that referred to a wireless standard. The current version is 802.11ac, but before that, we had 802.11n, 802.11g, 802.11a, and 802.11b. It was not comprehensible, so the Wi-Fi Alliance — the group that stewards the implementation of Wi-Fi — is changing it.
All of those convoluted codenames are being changed. So instead of the current Wi-Fi being called 802.11ac, it’ll be called Wi-Fi 5 (because it’s the fifth version).
I would have prefered dated versioning. I think that version year makes it contextly clearer whether a WI-Fi system needs replacing or not. If I see "Wi-Fi Version 5", I may not know if that is the most current version of several years old. But when I talk about my 2006 Honda Accord, it is quite clear I am driving an older car. Still, this is better than trying to understand if 802.11ac is newer than 802.11a or 802.11g etc.