You're being much too literal.
Saute comes from the french "sauter' which means "to jump'. It refers to the fact that you keep the food moving so it doesn't burn. There's so much moisture in spinach, even on a high heat you wind up steaming it more than anything else.
Put some olive oil and garlic in a medium hot pan, keep the garlic moving for 3 minutes (if the garlic starts turning brown turn the heat down), add the greens, turn up the heat a bit. Keep the greens moving so that they get lightly coated in the oil. Keep moving them around the pan until they're at their brightest green, add sea salt, take them off the heat, serve with lemon.