Yes, that's a flasher.
One way to figure out what an electrical unit is to find a wiring diagram for the year of your bike. With the diagram look for a unit with the same number and color of wires. Your flasher has 3 wires, one brown, one brown/white and a black wire.
This means your bike is a 70-76. The black wire is the give away. On the 70-76 this is a ground. In 77 they started using a self canceler on the turn signals and the black wire was changed to a green/yellow wire.
Up at the top of this page you will find an XS650 TECH button. Clicking this will lead you to a list of subjects. Under each subject is a list of topics about the subject. Clicking on one of these topics leads you to threads about the topics.
I suggest looking under electrical and then some electrical diagrams.
Leo