What does an Ethernet cable look like

If it's the common "CAT5", "CAT5e" or "CAT6", it's around 1/4 inch thick, blue, grey or purple jacket, and slightly bumpy due to the four pairs of twisted wires inside the jacket.

The connectors are most likely the rectangular clear plastic plugs known (incorrectly) as RJ45, and correctly as 8P8C, fitted to the cable with a special crimping tool, die tool.

The cable can be solid-core (cheaper, only suitable for wired-in cabling) or stranded (more expensive, suitable for patch cables and panel-to-computer cables).

When fitting connectors, be sure to use the correct ones (for solid core or stranded core).