What does wich mean?

The spelling "wich" is not a Word, it is a misspelling of "which" or "witch". These are the only 2 versions of these similar-sounding homonyms.

"Witch" we all know has historically meant someone, a female, who has certain powers.

"Which" is a selector type Word, as in:

"Which dress do you like?"

"Which" also connects parts of a sentence, referring back to a particular noun. For example:

The professor made two points, both of which were valid.

"Which" indicates more than one item or person, as in a group. For example:

Which dresses would she like to try on?

Which student pushed Johnny to the ground?

Which suspect did the victim identify?

Note: We need both "which" and "that" in sentences but it's important to know when and how to use each one.