méi 没 is a Negative Adverb in Chinese. It is used for "negation of completing an action", meaning the action is not completed or has not be completed. We put 没 before a Verb:

Subject + 没 + Verb ( + Object ) 。

Lǐ Lǎoshī méi shuō Yīngyǔ 李老师没说英语。
Teacher Li not (completed the action of) speaking English.
Teacher Li didn't say (anything in) English.
wǒ méi xué Zhōngwén 我没学中文。
I not (completed the action of) learning Chinese.
I didn't learn Chinese.
tā méi shuìjiào 他没睡觉。
He not (completed the action of) sleeping.
He didn't sleep.

Grammar 2: COMPARE 没 VS. 没有 · HSK 1

When using as a Negative Adverb suggesting "not completing the action of something", 没 and 没有 are interchangeable, and can be used like this:

Subject + 没/没有 + Verb (Object) 。

tā méi hē kāfēi 他没喝咖啡。
He not (completed the action of) drinking coffee.
He didn't drink coffee.
tā méiyǒu hē kāfēi 他没有喝咖啡。
He not (completed the action of) drinking coffee.
He didn't drink coffee.

没有 can be used to suggest "not have something" or "not own something", which is a Verb Phrase (没 is the Adverb and 有 is the Verb). 没 can only be used as an Adverb.

Grammar 3: COMPARE 没 VS. 不 · HSK 1

Both 没 and 不 can be used to express a negative meaning.

Many people say that 没 is for the past tense and 不 is for the present tense, but that’s not always the case. 没 can also be used in the future tense, while 不 can also be used in the past tense.

We’ll compare them again in details when we learn about past and present in the future.

In today's lesson, for negation of Dynamic Verbs (Action Verbs), here's the differences:

没 + Dynamic Verbs	不 + Dynamic Verbs
the negation is objective	the negation is subjective
the negation is an actual fact	the negation suggests people’s will or judgement
/	the negation is habitual

For example:

wǒ méi mǎi diànnǎo 我没买电脑。
I not (completed the action of) buying computer.
I didn't buy computer. - as a fact
wǒ bù mǎi diànnǎo 我不买电脑。
I don't (want to/ plan to) buy a computer.
I'm not buying a computer. - my plan

wǒ méi xiǎng nǐ 我没想你。
I not (completed the action of) missing you.
I didn't miss you. - as a fact, but I might want to miss you later
wǒ bù xiǎng nǐ 我不想你。
I don't (want to/ plan to) miss you.
I don't miss you. - my free will

When the action is habitual or is a usually thing to happen, we use 不 instead of 没. For example:

tā bù hēchá
她不喝茶。
She doesn't drink tea.
wǒ jiějie bú yòng diànnǎo
我姐姐不用电脑。
My big sister doesn't use computer.

Grammar 4: COMPARE 说话 VS. 说 · HSK 1

说话	说
to talk ~~something~~	to talk ~~something~~	to talk + something
to speak ~~something~~	to speak ~~something~~	to speak + something
/	to say + a quote