The interviewer here is trying to determine your level
of competence and talent with a role or task, not simply
whether you know how to do it.
So whatever your level of experience is with social media as it relates
to the job of real estate agent, try to focus your response
on measurable achievements and accomplishments
and how they might translate to the job you're currently interviewing for.
You can discuss past and present victories and display future potential
at the same time.
Craft your response then on how you've fixed or improved something,
changed a process, or developed new ways of doing things.
Go into enough detail to fill out the story but what you're really after
are sound bites and headlines, not all the ins and outs of it.