I call it the “SDF Boolean” node because it also includes difference and intersection modes, as well as attribute color blending.
If you get stuck, check out the documentation pdf that comes with it. It includes a basic description of each node, along with a simple usage example.
If you’re still having issues, don’t hesitate to send me a PM or ask a question on my topic. I’ll be happy to help you out!
If you’re looking for additional resources regarding signed distance functions, check out Inigo Quilez’s blog.
@Leonard_Siebeneicher also has some useful resources regarding SDFs and simulation nodes. The topic is also worth a read on its own — he includes a lot of important details about each advanced technique.