‘Layers’ are information related to the registered activities that can be displayed on the 'Map'. Each 'Theme' has a list of specific ‘Layers’ for viewing which can be selected together or individually.
In order to enable it, just check the desired box and then click on 
again.
Each Theme has a specific set of layers that can be enabled. The following links contain all Harvest and Spray themes.
Harvest
4.6.1.1- Harvest
4.6.1.2- Shaker Rolls System
4.6.1.3- Events and Stops
4.6.1.4- Time Range
4.6.1.5- Productivity
4.6.1.6- Speed
Spray
4.6.2.1- Events and Stops
4.6.2.2- Time Range
4.6.2.3- Overlapping
4.6.2.4- Speed
4.6.2.5- Applied Volume