An Exclusive Gateway indicates a point where the Process can take one, and only one, of multiple possible paths.
The path the Process takes is based on conditions defined on the outgoing Sequence Flows. The Sequence Flow with the condition that evaluates to true is followed. If no conditions evaluate to true, the execution will result in a runtime exception. You can avoid this by seeting a default Sequence Flow in the Conditions tab.
An Exclusive Gateway appears as a diamond shape with an X marker.
You’ll find Exclusive Gateway attributes and other settings within the Attributes panel, under the Attributes tab and other tabs.