Under the Chapter Equilibrium, Ionic equilibrium is a topic. So, just to answer your question Indicaors are an important topic in NEET Chemistry syllabus. This has been taken from the Information Bulletin itself for you: Under Equilibrium topic, you need to study:

Equilibrium in physical and chemical processes, dynamic nature of equilibrium, law of chemical equilibrium, equilibrium constant, factors affecting equilibrium- Le Chatelier’s principle; ionic equilibrium- ionization of acids and bases, strong and weak electrolytes, degree of ionization, ionization of polybasic acids, acid strength, concept of pH., Hydrolysis of salts (elementary idea)., buffer solutions, Henderson equation, solubility product, common ion effect (with illustrative examples