Current Time
When a key is selected you can see its time value here. You can toggle between frames and seconds with the Alt + F and Alt + T shortcuts.
Parameter Value
When a key is selected you can see its parameter value here.
Pointer: F
This is the current frame at the mouse pointer's position.
Pointer: TC
This is the current time in seconds at the mouse pointer's position.
Pointer: y
This is the mouse pointer's current Y value.
Pointer: f(x)
This is the curve's current Y value (=parameter value) at the mouse pointer's corresponding time. It can also be written as y = f(t).