This is the gold version of the standard Australian proof coin set for the year. It contains all the regular circulating denominations, in 99.99% gold and in Proof FDC grade.
The Royal Australian Mint says about this year's set:
"This 2020 Silver Proof Six-Coin Year Set heralds the formal launch of the newest effigy of Her Majesty Queen Elizabeth II on all Australian coins produced by the Royal Australian Mint. The effigy, which is the sixth portrait of the Queen featured on Australia’s coins since her 1953 Coronation, is adapted from a design by Jody Clark. This set, representing a new era in Australian numismatics, will be treasured by coins collectors and numismatists."
Coins dated 2020 were minted and released in October 2019 in Royal Australian Mint sets. Note that these mint sets refer to Jody Clark's portrait of the Queen as her "6th Effigy", which takes into account her effigy by Vladimir Gottwald issued (in Australia only) in 2000.