Top row is video timecode of a PAL video signal. 25 frames with 50 fields.

Second row is the A, B, C, and D frame cadence identification typically used for NTSC.
It is used here since the definition of repeated field cadence:

A Frame = 2 fields where timecode does not change between fields
B Frame = 3 fields where timecode changes between fields 2 and 3
C Frame = 2 fields where timecode changes between fields 1 and 2
D Frame = 3 fields where timecode changes between fields 1 and 2

The A, B, C, and D represent the original film frame.
There are two letters for every frame to represent the original film frame for the each of the
two fields for every video frame.

Each box is a video frame. There are 25 frames.

Each box contains two numbers. Each number represents the original film frame from a 24fps timeline.
Original film frames are identified as frames 1-24
This cycle repeats itself every second

There are two numbers in each box to represent field 1 and field 2.
The numbers show how 24 frames are evenly distributed to 50 field of 25 frame video.

The 12th frame is 3 fields long, and the 24th frame is 3 fields long.
All the rest are two fields long.

The last row represents whether the video frame is considered progressive or interlace based on the original frame content.
A frame is considered progressive when the video frame consists of the same film frame content (represented by the number or the letter)

There are 13 P frames (progressive) and 12 I frames (interlace).