如果使用串行逗号/ array_pop时未满足条件

Newbie here working on a simple post back form (complex for me actually). My goal is that if only one item is selected, the word 'and' would not print. The file works nice when three or more things are selected as it drops the last comma, but if it's only the the last element then i want to drop the 'and...' so that only the last element prints.Newbie here working on a simple post back form