The sprinkler source component is used to provide water to near by plants. Sprinkler source components can be added to any blueprint the same way you add any component in the components panel.
When you select a sprinkler source component in a blueprint you will have the settings shown below in the Details panel.
Here you can change this sprinkler source settings for the blueprint you select it in, you can hover your mouse over each settings name to get a tooltip with more info about each setting.
You can enable and disable the sprinkler source using the Enabled setting, this can also be changed using blueprint nodes, there is an example of this in the BP_MasterSprinkler blueprint.
The Water Add Time is how often the plants within the range of the sprinkler source component will receive water.
The Water Add Amount is the amount of water the plants will receive.
The Water Add Radius is radius around the sprinkler source component that will receive water.
When ticked on Use Blocking Trace Check does a line of sight check to only add water to plants that are not blocked by other objects.
The Block Trace Channel is the trace channel used to detect objects that block water being added to plants.
Block Trace Debug allows you to see the Block Trace in game, this can be used to find object that are blocking plants from receiving water.