Does "have" also mean "must"?

It is partially correct. "have", does not mean the same as "must", but "have to" does and is in fact what is normally used. For example "I have to study." is a common phrase. "I must study" is less common. "I have study" is wrong and confusing. note that putting the word "to" in front of a verb makes it an infinitive, although "to" has other meanings when put in front of other kinds of words, such as nouns. "Have" is a verb, but it is a transitive verb, which means that it usual references something else. Note that "have" can have other meanings, such as in this sentence where it means "possess". I can not read Chinese, but your usage is perfect English.

Have TO is close to must . However, must is much stronger word than have to. You can say it to your child, etc. Have TO is milder and can be used more freely.

From the point of view of English, "have to"--but not "have"-- is the same as "must." I have to go=I must go. We cannot say that "have" means "must."

We do not say, "I must to go." That isn't English.

No, because inserted into the same sentence would have different meanings.
As in:
"You MUST go!" This implying there is something you need to do.
"You HAVE go!" And this one implying that 'go' is an object that you have in your possession.