Describe how to use a reference point and a set of reference directions to define the position of an object.

in the most general possible way to answer this; suppose that the reference point is the door of your house, now you can put the door as the point (0,0,0) in an cordinate axis, now, with this in mind, you can describe the exact position of every object in your house in that cordinate axis where the door is the reference point.

for example, "the table is five meters right in front of the door" can be described by the point (5, 0, 0) (where the axis can be defined by you, as it is more convenient)