Standard Aussie polarity convention means that a black is a soft...

Standard Aussie polarity convention means that a black is a soft (the interface is fast/dense rock overlying slower/less dense rock). A white is the opposite and is a hard. The coloured wireline log is a Gamma Ray (GR) or possibly a petrophysical estimate of the lithology (Vcl). Regardless the area between the prominent black and the prominent white traces shows the wireline curve strongly to the right suggesting a shale while the rock above is a hard sandstone or carbonate. Similarly the intense curve to the left (reddish) is undoubtedly the top of a carbonate (the Rafa reservoir).
An interpreter would now spatially map though two 'horizons' along with many others above and below to produce time maps and then convert these to depths. As you can see from CEO post later, the correlation of the horizons is not obvious but using the full 3D to look at other angles allows a detail picture of what the layers of rock may look like.

Note the details may be slightly different as I am an outsider but hope to answer some of the questions asked for a layman.

There is some skill in the interpretation and like all science there are multiple theories which fit an available dataset. The beauty of this industry is that your theory is only as good as the results of your next well, which means one proposes a theory with a degree of humility not seen in some more academic fields.

And of course there is the old joke - 'if you put 2 geophysicists in a room with seismic, you will get a least 3 different answers'. The other joke about 'what do you want it to be?' is left for another time.