In regular expression what * represents?

It has no particular meaning in regular expression.*

*Sometimes it means "explanation in a separate paragraph below.

Since English has "bad words", people might alter the spelling to get past censorship. For example you can say excrement, but the shorter word is "bad" and must be misspelled, sometime sh*t, sometimes sh!t, sometimes shirt, or other inventions.

There are some other random usages.