Cambridge dictionaries use various labels and codes, among them are:
[C] Countable noun: a noun that has a plural.
[U] Uncountable or singular noun: a noun that has no plural.
[S] A singular noun.
I do not understand the difference between a singular noun and the singular form of a countable noun. For example, with the entry "word"
sense 1: noun [C] a single unit of language which has meaning and can be spoken or written
sense n: noun [S] a brief discussion or statement: The manager wants a word.
What if the manager wants to have several discussions? Is it impossible for us to say "The manager wants some words." because "word" here is singular? I am confused.