If someone were to ask you how it is you talk about more than one of the same kind of thing at a time in English, you might tell him a number of things. Most of us would say, "Add an S." A linguist might say, "If the object in question's lexical reference ends in a vowel, add a voiced alveolar fricative. Unless, of course, that reference should end with a non-approximant consonant, in which case you will have to precede the voiced alveolar fricative with a mid-center vowel, excepting of course cases in which the non-approximant consonant is also any manner of unvoiced fricative or plosive, in which case you will have to drop the voicing of your alveolar fricative." One of these will be easier to understand, and one of these will be more accurate.
You probably weren't expecting them to both be the former.
Yes, it's true. You might think the linguist is onto something here, what with all his fancy-talk and such. Truth is, his explanation is a rough approximation of a single convention disguised as fact, and is the reason you shouldn't trust some o' them academic types. What he says is essentially, "Make a 'z' sound unless it ends roughly, in which case make the '一' sound in '한글' and then the 'z'. You might also make a 'normal s' sound now and again." That might be true for him, but I find myself often preceding my voiced alveolar fricatives with a vowel more to the tune of a near-close near-front unrounded (which is the 'i' in 'which'). But that's just me. I know lots of people whose method of pluralizing nouns in English is different entirely, at least when it comes to linguistic jargon. If you are transliterating things into the IPA (International Phonetic Alphabet) at a university, and they are looking for one answer, do not give that school your money.
The first response, on the other hand, is quite nice. In just three words, they have effectively communicated all the many ways people in English pluralize non-exceptional nouns, by referring to what a linguist, as fate would have it, would call an "allomorph". Essentially, it means that we understand S's to make a variety of sounds, all of which will demand some manner of space in between themselves and certain other consonants, and which will manifest itself in natural and appropriate ways when someone speaks. Here's an example:
Note the difference in the pronunciation of the letter S in each word? The preceding consonants in each case are articulated in the same spot, but the difference is that 'traditional t' sounds are unvoiced and 'traditional d' sounds are. Your following 's' will voice itself or unvoice itself accordingly. Try screwing around with different combinations, see how it works for yourself. Learning neat little nothings like this is what will really put you on your way to realizing a second language.
More to follow!