Earlier, it was mentioned, incorrectly imo, that the EU and global power uses only one line for power.
Most of the world is 220V (240V) single phase, residential, at 50 Hz.
The std residential single phase service uses 2 lines for power.
And a green/yellow safety ground, not used at all.
Unlike in the US, plugs are not keyed.
You can use either line, since its AC, and both lines carry an identical load.
Typically, up to about 4-6 kW is single phase, and around 4-6 kW you start to get 3-phase used, for example for saunas (or larger jacuzzi).
Most new EU residential installs have 3-phase at the fuse box, as standard.
And typical power levels are 10-15 kW, up to 20 kW, new, in the EU.
I have about a 20 kW install, older, in Spain, and this is quite unusual.
Technically, the service is iirc about 14-16 kW, 380 V 3-phase, with all appliances done at 220V single phase.
But I have 380V 3-phase wired in several places, just not in use at the moment.
So I could connect say an electric car plug, and charge at 14-16 kW, if I wanted to.
Any electrician can connect the plug, and it costs about 100$ (legal install, no paperwork necessary).
Since I already have the service, and internal wiring, the current installs like mine are grandfathered in.