How must I answer the question?

I had interviewed with the company for e-marketing job, the interviewer have a question : Are you sure effective ? ( that’s mean : will the company be sold goods(or customer) in a short-time ?)

I have good e-marketing technical but I can’t sure I can sold goods in short-time.

I don’t know how the best answer for this question ?

I’m very happy for answering me.
Sorry , my english isn’t good.

Thank you for helping me.

You may say something like: “I’m sure that I’m good in technical e-marketing and I’m sure that I can sell goods for your company. I plan to do it as soon as possible and as much as I want, I really target on selling it the shortest time. I have all the capabilities and skills and resources to find leads for a faster sale conversion. And if given a chance, I would like to start it the soonest possible time as I can’t wait to help you and your company gain more income from right away.”

Hope this helps.