This is an interesting and somewhat rare response. It means they’re interested enough to keep it under consideration, but—for some reason—not ready to commit. Make sure to keep the publication updated on any changes in the status of the submission’s availability, but don’t bother sending revisions. When a publication wants changes, they will ask for them, or have one of their editors work on the piece. (This is true for fiction and creative non-fiction essays, which are submitted in their entirety. With an article for a magazine or newspaper, you usually pitch the idea first and the publication will discuss with you any tweaks they want before they buy it and you write it.)
Many publications even extend acceptances with the contingency that edits meets their specifications. More likely, they’re not publishing the article because it doesn’t fit in with what’s appearing in their upcoming issues, or they’ve already published something very similar recently, or upcoming issues are full. And no amount of editing will fix those problems.
Follow up in a few months about the submitted work to see if they’re still interested. You might even mention you’ve made some edits. But if you do this, be brief and focus on the kinds of changes you’ve made, such as strengthening the flow or including more quotations from an interview.
In the meantime, keep close tabs on the upcoming issues and use what you learn about the publication and their enthusiasm for your work to send a new piece or pitch a different idea. And make sure to shop around the one they’re holding on to with other publications, too.