Answer:
They want to know what I am doing because the question ¿Qué estás haciendo? means what are you doing? In this way, estás is the conjugation of the verb estar for the second person singular. On the other hand, haciendo is the gerund of the verb hacer. So estar + a verb in gerund form the present progressive. Finally, this is an example of a dialogue:
- ¿Qué estás haciendo?
- Estoy jugando fútbol
IN ENGLISH:
- What are you doing?
- I'm playing soccer
