Watts is the energy consumed "right now" (which is the product of Volt x Amps), but needs a time dimension to give a measure of historical consumption, which is where the Watt Hour (Wh) comes into play.

While most people are aware that X consumes Y Watts, few consider how much that addes up to over the course of days or weeks.

Few people are aware that a simple ethernet switch will roughly consume 1W per plugged in port, so an 8 port switch might consume 8-16W of power just sitting there, so 4-9 kWh/month.

My old homelab used to consume around 300W when idle, meaning it was consuming 300 * 24 * 30.5 = 219 kWh/month, and with electricity prices reaching €1/kWh, that suddenly becomes A LOT of money to have a Plex server available 24/7.