In the Timeline, you can see a list of your past actions. To see how your blood sugar was affected by those actions, press on one of the actions and you will see the record summary.
The action you select will be shown along with all other actions that were affecting your blood sugar around that time, from 1 hour before to 5 hours after. Here you can see how your blood sugar reacted to each of those actions. The action bars show how long each action was likely affecting your blood sugar for and the bolder the colour, the greater the affect the action likely had on your blood sugar - just like on the What's Ahead screen.
You can scroll the bottom half of the screen up and down to see all actions affecting you at that time and to see how they align with your blood sugar.