The RDF format is used to define graphs using a series of triples (the two nodes and the labeled relation).
RDF is used on the Web in particular and advanced Logseq users are looking for using RDF and standard schemas to make their graphs part of a larger collaborative database that can be searched with the tools we already have.
At the moment exporting to RDF means that you can explore some data from your Logseq graph using third party graph visualization and analysis tools. You can also use other tools that generate figures from RDF.
@post thank you so much for this explanation. I will update the post tomorrow and add an embed with your explanation. Thanks a lot.