Luiz - WFS is a specification published by the Open Geospatial Consortium (OGC) for serving geographic features on the internet. When a layer is published with WFS capabilities, the data can be acccessed by OGC-compliant WFS clients. You can read about OGC Standards and Resources here. RE: the ArcGIS Pro relationship of sharing, there is some veribiage midway down on this page.
