Conversation 2 in Lesson 2 mentions 'a melting ice-cream bar'. The 'Grammar Focus' table clarifies: 'melting ice-cream bar | What type of ice cream? | a melting ice-cream bar | melting works as an adjective'. Therefore, 'melting' describes the 'ice-cream bar'.
Class 6 › English Grammar and Composition › Chapter 5: The -ing form of Verb: Gerund & Participle › Topic: The -ing form of verbs: Gerund
Aligned to the NCTB national curriculum.