个 (gè) is the most commonly used measure word. It can be used in a pinch for any noun if you can't think of a more precise measure word. (Although you might not sound quite as smart, you'll still get your point across). Also, for many nouns, 个 (gè) is the only correct measure word.
The general structure for 个 (gè) and measure words in general is:
Number + 个 + Noun
Any time you want to state how many of a noun in Chinese, you probably need a measure word. First get used to how they are used with 个 (gè).
- 一 个 人yī gè rénone person
- 四 个 朋友sì gè péngyoufour friends
- 三 个 苹果 手机sān gè Píngguǒ shǒujīthree iPhones
- 五 个 星期wǔ gè xīngqīfive weeks
- 六 个 月liù gè yuèsix months
- 两 个 老婆liǎng gè lǎopotwo wives
- 十 个 男人， 七 个 傻， 八 个 坏。A line from a songShí gè nánrén, qī gè shǎ, bā gè huài.Ten men: seven are fools, and eight are bad.
Omitting the Number
Verb + 个 + Noun
If the number is one (1), you can omit it and use 个 (gè) by itself. This is similar to "a" or "an" in English, for example in "a person" or "an idiot." (The tone on 个 (gè) is normally somewhat de-emphasized in this usage, but still written as fourth tone. You don't need to stress about it, though.)
- 他 是 个 老外。Tā shì gè lǎowài.He is a foreigner.
- 我 有 个 儿子。Wǒ yǒu gè érzi.I have a son.
- 她 是 个 好 老师。Tā shì gè hǎo lǎoshī.She is a good teacher.
- 你 想 吃 个 包子 吗？Nǐ xiǎng chī gè bāozi ma?Would you like to eat a stuffed steamed bun?
- 老师 ， 我 有 个 问题。Lǎoshī, wǒ yǒu gè wèntí.Teacher, I have a question.