Most people don't ever really stop to think about it but English has many ways of making a word plural and has a lot of words that are only plural or can not become plural. Some of this is logical. You can't really count milk in the same way you can count CDs. Some of this, while not quite so logical, is sensible. You can count rice, but who wants to. Besides that, if you need to count rice you just count the "grains" and you are happy. Sadly, some of this is just grammatical. You can count money and yet the word "money" is uncountable and can not easily go into the plural. It is odd that when we ask "how much milk" we get a volume measure but when we ask "how much money" we get a digital number.
Well, guess what, shock of shocks, this same sort of thing happens in every language and Latin is no exception.
English also has several different ways of creating the plural. Most words use the "add s" rule but not all. We have the "ren" ending for child which used to be used much more often. We have the "en" ending for ox, which also used to be more common. We have some words that just don't change at all and easily transition from singular to plural depending on the context.
Well Latin has a number of different ways of creating the plural and in a Latin class you would spend a lot of time memorizing list of declensions. However, for this lesson on this site I strive to make things as easy and and as little difficult as possible while still subjecting you to real Latin. It is times like these that knowing the gender of a word is important.
Gender is one of those "difficult" things in Latin but you can actually learn the plural ending for words with no gender very quickly; it is just "a". You can practice this with English words. Look around the room for odd shaped objects, like say a computer's printer. The reason I say odd shaped is that there tends to be a pattern with this whole gender thing. Flat and smooth objects are Feminine. Long and skinny objects are masculine. When your vocabulary is large enough you will almost begin to predict the gender of an object even before you know the word.
Anyway, find an odd shaped object like a printer. Now change the pronunciation of the word to match the spelling or change the spelling to match the pronunciation, it is up to you. I prefer to change the pronunciation, to really get the Latin feeling going through me. If you do like me you will way "preent-air" since "i" in Latin makes that long "e" sound of English. Also, notice that we don't allow the final "e" and "r" to melt together, we keep them separate so that the end of the word sounds like the English word "air". If you can get the "r" to roll a little bit that would be even better. Think Zoro or Cathwoman.
Now to make this word plural we just add our "a" sound to the end. This gives us "preen-te-ra". Since the stress of a work in Latin is usually on the second to last sound we will say "preen-TE-ra". Since we decided that the word printer would not have gender, it means that this words will have the same form for both the subject and object of a sentence.
Now if you happen to have a video game controller anywhere abouts you can do the same thing to it. You can play the video game by yourself and use only "unum controller" or you can play with a friend and then you will use "duo controllera". The vowel sound in bold is to get the stress.
Now practice by yourself. You can practice with anything. Start Latininzing. Then when you study real Latin words, remember to get them into your mouth as fast as you can.