The timeline in the sow card, is the part of the card that show the events of the sow separated by cycles in order

Access: Management > Breeding Herd > Analysis Center > Sow card

Note that in the first row from bottom to top, we start as cycle 3. The first event presented is the purchase date of the sow. Note that she was bought pregnant and already in the third cycle and the line continues showing the days of breeding: 34 days.

The next point is: farrowing, there were 18 liveborn.

Then the line shows the days of lactation 22 days of lactation, with no piglets being fostered on or off.
The next stop is the next event, which is weaning, the 18 piglets were weaned.
The next cycle will start only at the next mating, which marks the end of the current cycle and the beginning of the fourth cycle of this sow.

Note that the system shows the IBWM days (interval between weaning and mating) ending cycle 3 and cycle 4 starts on the same date.

Note that what has already been entered appears with the consistent gray line, until the coverage of cycle 4.
The dotted line are possibilities in face of what has not yet been entered, the system shows the following possibilities:

There may be a heat repetition at 21 days followed by a second heat repetition at 42 days or delivery at 115 days scheduled for 10/03/2021.

Also note that there is a caption in the upper right corner, which tells you what the lines are saying.

The solid gray line refers to an event entered;

The solid red line informs an event that generated reproductive loss;

The gray dotted line shows the possibilities of future events;

The yellow line (which we don't see in this sow yet) shows partial weaning