When using the Yandex.Maps API, it is easiest to imagine the map as an image of an area or object, made up of points that each correspond to a coordinate pair.
In actuality, the map is made up of several layers placed on top of each other, and each layer is divided into a multitude of square sections called tiles. When displaying the map, all the tiles are combined, the layers are placed over each other, and a unified image is formed. The unified image is generated automatically, and this process is hidden from the user.
You probably don't need to understand how the image is created unless you need to create your own custom map. For the majority of users who are using standard sets of Yandex maps, it is fine to think of the map as it is described in the first paragraph.