Kniphofia uvaria, commonly known as Tritoma, Torch Lily, or Red Hot Poker. It’s easy to see why. I can see these alongside a pool, with some ornamental grasses behind them, or intermingled with them.
They’re quite easy to take care of. They’ll grow in pretty much anything, though don’t make the soil too rich, and make sure it drains well. Don’t let them dry out completely.
They’re quite an unusual specimen as an ornamental plant… unless you live in Australia where they’ve naturalized and become weedy. Then you’ve probably seen them more than enough.