Classifiers are used with nouns to count things in Vietnamese. The structure is the quantity + classifier + noun. There are many classifiers in Vietnamese, but the 2 that you will use the most are cái + things and con + animal/living things. Example:
|hai||cái||điện thoại||di động|
Some other useful classifiers: quả + fruit, cuốn sách (book), quyển vở (notebook), tờ báo (magazine, newspaper).
The (almost) full list of classifiers can be downloaded as a PDF here. There’re about 30+ of them (and yes, I know all of them by heart).
About the photo above: It was taken by my friend in her garden in Vietnam. Cây khế and quả khế are common tropical fruit & well-loved by the Vietnamese. And this is something to know before picking your quả khế:
|một số (some)||quả||khế||ngọt|
You can view the original photo here on Flickr.