Why are you applying for this job? (or) Why this role attract you? (or)
 

By this question the interviewer wants to know that -

If you fully understand what the job entails
How well you might match their requirement
What appeals to you most about this job
Before answering this question, take your own time an answer in way that convince the interviewer. Explain your qualities according to above stated points.

For example -- I have applied for this vacancy because it is an excellent match for my skills and experience. This role is exactly the sort of role I am currently targeting and I am confident I will be able to make a major contribution.