You can make a paper hexagone and fold it to a chair conformation. With little imagination, this will help you to understand which pair of axial substituents corresponds to a cis- or trans-(geometrical) conformation.
But if it if still not comprehensible, you can imitate axial substitution with e.g. pencils, matches, toothpicks, plastic straws, etc. that are perpendicularly fixed on the edges of the hexagonal paper-sheet.
Also, this will help you to observe that axial/equatorial substituents pair correlation with cis- or trans- geometrical conformation, is not identical for each of 1,2, 1,3, 1,4, 1,5 and 1,6 substituents pair.