Advanced Research and Design, a.k.a. theoretical science AR&D, or R&D, is a practice of developing novel technologies, typically in a way that can drive new business approaches or products. R&D is practiced heavily in academia along with applied science.
In software development terminology, it is analogous to 'back-end' work, supporting customer-facing efforts in potentially multiple products or multiple applications. Where other data analysts might use machine learning tools for other applications, an R&D role would be more likely to try developing a new or improved machine learning tool altogether.