Uluru is an inselberg, literally "island mountain", an isolated remnant left after the slow erosion of an original mountain range - from Wikipedia. The rock has been shaped by wind and water erosion over the millenia.
is due to iron oxide (rust). Before the existence of Stromatolites (cyanobacteria), there was little or no oxygen in the Earth's atmosphere. Then, over billions of years the Stomatolites did their work and brought further life to the planet. When an excess of O2 occurred, the iron was subjected to oxidation as the sandstones were formed.