This is a "baby" version of the standard Australian Brilliant Uncirculated coin set for the year. It contains all the regular circulating denominations except the 50 cents; instead of the "definitive" Coat of Arms type, it has a special Possum Magic non-circulating 50 cent collector coin.
The Royal Australian Mint says about this year's set:
"For the third and final time, in 2020 the Mint’s annual baby set will feature the beloved Australian children’s book Possum Magic, written by Mem Fox and illustrated by Julie Vivas. A special 50c coin and a colour printed token in this set celebrate the beautiful illustration and whimsical sweetness of the book. An ideal gift for your own little possum."