There are three stats in Numenera: Might/Health, Speed/Agility, and Intellect/Personality. But we just call them Might, Speed, and Intellect for simplicity. They represent exactly what you would think they do.
Any kind of action taken by a player character in the game can be assigned to a stat. Jumping is a Might action. Dodging an attack is a Speed action. Talking your way past a guard is an Intellect action. And so on. This is only really relevant, however, if the action in question is one that the player really wants to focus on. To do this, he or she spends points from the relavant stat to put “effort” into the action. This makes the action easier to do (and thus, makes it more likely to succeed. Points from stats can be regained, of course, but it’s still a finite resource. Thus, a player should only put effort into the actions important to them.