A wired ethernet cable still beats wi-fi for anything that cannot tolerate a dropout — a desktop, a console, a smart TV streaming at 4K, or a work-from-home setup carrying video calls.
The category number is the thing to check, and it is printed along the jacket. Cat5e handles gigabit and is fine for most homes. A cat6 cable adds headroom and better shielding against interference. Cat6a and Cat8 go further again, though almost nothing in a house will use that headroom today.
Buy an ethernet cable for the equipment you actually have rather than for the biggest number on the shelf. The router, the port and the cable all have to support a speed before you see any of it, and the slowest of the three decides the result.
