The first image is a basic oval. It is made of eight (8) 45 degree curves with a radius of 11", several plain straight track pieces of various lengths, one rerailer which looks like a road crossing, and one feeder.
A feeder has some kind of electrical connector; its used to connect your layout to a power source. Large layouts may need several feeders. Frequently advanced modelers solder wires directly to track pieces instead of using feeders
A rerailer guides the wheels of locomotives and train cars back onto the rails if they have slipped off. You would normally put this at the end of a straight section where you can put locomotives and cars on the rails.