USB Type C in theory is the best connector ever, but in reality you need a dissertation to understand it completely. The transfer speed denotes the speed with which the data is able to be carried over the cable.
But generally you can group USB Type C cables in to some small groups:
First you have USB 2 dumb cables. Those are the cheapest and Support the least features. They should be able to charge with up to 60W (20V, 3A), but in the early days of usb C, there were many cables which lacked a certain resistor, which could lead to damage of PSUs or devices (and were a fire hazard as well). Data Transfer: 480Mbit/s (~40 MB/s), most likely no other features.
Then you have USB C 3.0/(3.1 Gen 1/3.2 Gen 1) Cables: Also minimum of 60W, 5Gbit/s Data Rate(~500 MB/s), Support of Alt-Modes like Display signals. USB 3.0/3.1 G1 are the same standards, the marketing gurus of the USB-IF just found the names too logical and thought that (normal) consumers should not be able to understand it.
USB C 3.2 Gen 2: Same as usb 3.1, but up to 10 Gbit/s data rate (1GB/s)
USB C 3.2 Gen 2x2: up to 20 Gbit data rate (2GB/s
USB 4: up to 40 Gbit data rate(4 GB/s), supports Thunderbolt 3 as alt mode. Thunderbolt is a protocol that confusingly uses USB C as the connector since v3. Thunderbolt supports cool stuff like 4 PCIe 3.0 Lanes (I.e to connect an external GPU to your laptop or mini PC. Thunderbolt or USB 4 Cables must support 100W charging, but they are expensive and only available in short lengths (think little more than 1m is the maximum)
Now comes the even more confusing part: every USB type C cable can come with a marker chip that can denote its charging capabilities. If a marker chip is present, then you can charge with more than 60W.
Depending on what kind of docking station you buy, you either don’t need a cable at all (because it’s built in into the docking station itself, I.e the dell USB-C docks (Cable is pretty short, think 0.5m, for the dells also non replaceable), and Lenovos docking stations also come with the cable included). You just need to make sure, that the docking station itself has enough Power Budget for your Laptop ( would not choose one with less than 60W, best would be with 90W+). Then you just need to make sure that you’re either buying a Thunderbolt Dock or a usb c dock. A normal usb c cable could cause issues with a Thunderbolt dock (but not Vise versa!)
Also check the Packaging contents, most of the time a cable is included in the box.