What is the function of mortar in brick walls?

A typical brick wall structure normally contains the following components:
(i) a coping on top of the brick wall to protect it from weather;

(ii) a firm foundation to support the loads on the brick wall; and

(iii) a damp course near the base of the brick wall to avoid the occurrence of rising damp from the ground.

Bricks are bedded on mortar which serves the following purposes:
(i) bond the bricks as a single unit to help resist lateral loads;

(ii) render the brick wall weatherproof and waterproof; and

(iii) provide even beds to enhance uniform distribution of loads.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.