So there’s a little rule we all learned at some point in school regarding making a word plural. It’s pretty simple, actually: add the letter s or the letters es to the end of the word if you are indicating more than one of something. There are a few exceptions, but for the most part, that’s how it works.
For some reason, most of the people I encounter think that the proper way to make a word plural (as in, more than one) is to add an apostrophe before the s. That apostrophe makes me want to stab someone in a murderous rage. Not necessarily the person committing this baffling error, but perhaps the lowered scholastic standards that let people progress past grammar school, high school, hell, even college, without ever learning that this is wrong and infuriating.
Have I lost you? Here are some examples:
I have one dog. You have two dogs. Nobody has three dog’s, because that is wrong and weird and the apostrophe doesn’t belong there.
One dress. Two dresses. One glass. Two glasses. One earring. Two earrings. One letter. A whole alphabet of letters. Do you see any apostrophes? Nope, because we’re forming plurals. You want to indicate more than one of something? No apostrophe! Since I see way more of the apostrophe being used when it shouldn’t, rather than the other way around, I’m just going to go ahead and say that if you’re in doubt, leave the apostrophe out. See, it even rhymes.