When you click on the icon placed on the left side of a slider which adjusts a parameter, a window like the following will be opened. Such sliders can for example be found on the players' audio effects. This window was opened by clicking on the treble clef icon beside an audio file player's pitch slider.
The window contains a larger slider for more precise adjustment of the respective parameter, and a group of keyboard-like buttons above it. Each button will set the parameter to a specific value when clicked, in a way that the parameter can be adjusted in fixed steps. Instead of clicking the buttons, you can also use your computer keyboard. Use the preferences to define how to map its keys to these buttons. By default, the Y or Z key (depending on your keyboard layout) in the upper row of your keyboard's alphabetic keys is mapped to the button in the middle. The buttons left- and right-side of it are by default mapped to the keys on the keyboard the same way as keys on a piano keyboard, where the Y / Z key maps to the Do / C key of an octave and the black keys are mapped on the number keys row in the computer keyboard.
The parameter keyboard is mostly useful for the pitch parameter, where one step corresponds to one half tone, so that you can transpose the audio in an accurate way.
When you click one of these keyboard buttons, the parameter will immediately jump to its new value. Just like you can animate parameters using sliders, you can make the parameter keyboard smoothly animate the parameter to the new value instead.
To do this, open the parameter keyboard's contextual menu by clicking on any of the buttons using the right mouse button or the ctrl-key. By selecting "Animate", you can turn on or off animating the parameter. You can also select a custom animation in "Select Animation...". Note that this custom animation only applies for the keyboard of this parameter. It is neither linked to the default animation of the parameter, nor to the keyboard animation of any other parameter.