Select an object with animation. > Views menu > Show Key Times
Key Times shows the frame numbers along a displayed animation trajectory. Key times correspond to the settings in Time Configuration for Frames or SMPTE. By default, key times are shown as frame numbers.
To display trajectory time values in the viewport:
On the Display panel > Display Properties rollout, turn on Trajectory.
Tip: If the rollout controls are unavailable, right-click the object in the active viewport, choose Properties, and in the Display Properties group, click By Layer to change to By Object. This will make the Trajectory option become available.
Choose Views menu > Show Key Times.
The time values are displayed as white numbers along the trajectory. They remain displayed in red when the animated object is deselected.