The G20 has 21 members, and two of them are not countries
The Group of Twenty has 21 full members: 19 sovereign countries and two regional blocs. The 19 countries have all been members since the group was founded in 1999, and so has one of the blocs. The other bloc was admitted as a permanent member at the New Delhi summit in September 2023, which took the count to 21. Other guests attend every summit without being members. Spain is a permanent invitee, and bodies such as the UN, the IMF, the World Bank and the WTO are standing guests; none of them counts here.
Name them all first. Then name them in two groups: the 19 countries, and the two members that are not countries.