Countable and uncountable nouns

It's important to distinguish between countable and uncountable nouns in English because their usage is different in regards to both determiners and verbs.

Countable nouns

Countable nouns are for things we can count using numbers. They have a singular and a plural form. The singular form can use the determiner "a" or "an". If you want to ask about the quantity of a countable noun, you ask "How many?" combined with the plural countable noun.

Singular	Plural
one dog	two dogs
one horse	two horses
one man	two men
one idea	two ideas
one shop	two shops

Examples

• She has three dogs.
• I own a house.
• I would like two books please.
• How many friends do you have?

Uncountable nouns

Uncountable nouns are for the things that we cannot count with numbers. They may be the names for abstract ideas or qualities or for physical objects that are too small or too amorphous to be counted (liquids, powders, gases, etc.). Uncountable nouns are used with a singular verb. They usually do not have a plural form.

Examples

• tea
• sugar
• water
• air
• rice
• knowledge
• beauty
• anger
• fear
• love
• money
• research
• safety
• evidence

We cannot use a/an with these nouns. To express a quantity of an uncountable noun, use a word or expression like some, a lot of, much, a bit of, a great deal of , or else use an exact measurement like a cup of, a bag of, 1kg of, 1L of, a handful of, a pinch of, an hour of, a day of. If you want to ask about the quantity of an uncountable noun, you ask "How much?"

Examples

• There has been a lot of research into the causes of this disease.
• He gave me a great deal of advice before my interview.
• Can you give me some information about uncountable nouns?
• He did not have much sugar left.
• Measure 1 cup of water, 300g of flour, and 1 teaspoon of salt.
• How much rice do you want?

Tricky spots

Some nouns are countable in other languages but uncountable in English. They must follow the rules for uncountable nouns. The most common ones are:
accommodation, advice, baggage, behavior, bread, furniture, information, luggage, news, progress, traffic, travel, trouble, weather, work

Examples

• I would like to give you some advice.
• How much bread should I bring?
• I didn't make much progress today.
• This looks like a lot of trouble to me.
• We did an hour of work yesterday.

Be careful with the noun hair which is normally uncountable in English, so it is not used in the plural. It can be countable only when referring to individual hairs.

Examples

• She has long blond hair.
• The child's hair was curly.
• I washed my hair yesterday.
• My father is getting a few grey hairs now. (refers to individual hairs)
• I found a hair in my soup! (refers to a single strand of hair)

sumber :

http://www.edufind.com/english-grammar/countable-and-uncountable-nouns/