White circle with black cross inside…

[Tom Matthies]

It means that the frame you are parked on has not rendered itself yet for playback.
If you have a lot of filters or effects on a frame it will take a second or two to render itself when you park the playhead on that frame. Once the circle goes away, the frame is showing a fully rendered scene.
Tom

[Diego Villalba]

Thank you Tom.
Best wishes.

Diego

Die Go