Metallic character is defined as the tendency of an element to lose its outer electron.
Along the groups :
As we move down the group the electrostatic attraction between the nucleus and outer-electron decreases due to increase in the distance from nucleus of outer electron with increase in size of sub-shell orbital.The element will lose electron more easily. So, finally down the group metallic character increases.
This factor come into play for s-block element of Group-1,2
Non-Metallic character is defined as the tendency of an elements to gain an electron which depend on electronegativity.
Along the group :
Since electronegativity character decreases down the group for p-block elements and thus tendency to gain electron decreases, the non-metallic character decreases down the group
This factor comes into play for p-block elements from Group-13 to 17