It just means that you can run industrial gear; maybe was owned by a keen potter previously. Big kilns need 3 phase power. No it isn’t common for domestic, but I have a few friends with big shed that have 3 phase power for machining tools.

Depending on what capacity the supply has; e.g. if you have a smallish 80A supply you can run a a good sized CNC mill in you shed.

Three phase is useful for industrial motors or if you need more than 200A service. If I wanted to add another car charger in my garage and use them at the same time, they would have had to bring in another phase.