A point is a location. On the 2D coordinate plane, it's described by (x,y). Think of it like an address or like latitude/longitude. A point is an undefined term in geometry as it doesn't build off of smaller elements.
if that red segment, GJ, is parallel to the AE base segment of the triangle, then, the segment GJ is the midsegment of the triangle, and by the side-splitter theorem, those two triangles are similar.