"The soup is very hot."
Translation:Η σούπα είναι πολύ ζεστή.
Yes, "πολύ ζεστή" is "very hot" and "πάρα πολύ ζέστη" is even hotter. So, "extremely hot" as you say is possible as well as "too hot".
For this sentence, you could have translated it as: 'very hot', 'too hot', 'much too hot', 'really hot'.
I don't understand what "It" refers to in ''It was used in the same sentence in another exercise but the English translation was identical.''
If you could please give more specific information we would be able to make sure all sentences agree on the translation.
Right I see both sentences now. One says "Η σούπα είναι πάρα πολύ ζεστή." and one says "Η σούπα είναι πολύ ζεστή." And as I said both can be translated as "very hot". For " πάρa πολύ ζεστή" there are further alternatives such as "too hot" "really hot". There is not set temperature at which something is called "very hot" versus "too hot".