How do animation frame counts and framerate translate to engines like Unity?

I’m quite new to creating animations in Blender, and it doesn’t seem obvious to me how to “time” animations properly.

In Blender you seem to be able to choose the number of frames your animation takes, and then a framerate to play it at. In games, you want the animation to take a specific amount of time, and use however many frames necessary depending on the person’s framerate, which likely will be variable.

Is there a way to make animations time dependent in Blender?