on what the Buddha taught
Ekaggatā is often translated as one-pointedness, singleness, unification.
These translations are descriptions for what, in this context, we normally call focus. Focus reminds of holding a lens in such way the sunlight converges, unites, unifies, into a small area in order to create a burning mark or a fire. The light is then concentrated. Focus of mind (cittassa ekaggatā) is what concentration is (MN44).
Ekaggatā focus.
Cittassa ekaggatā focus of mind (concentration).