i not sure what is the single quote means...
the example like this :

if (value=='a')

Thank you 4 helping :)

its says the character 'a'.
Like we represent a string using double quote, e.g. "test string", we represent a character using single quote, e.g. 'a'.

>>i not sure what is the single quote means...

Its usually used with char variables :

char quit = 'n'; 
if( quit == 'n' ) 
   cout<<"Still playing\n";