Match Condition Filter can be used in case other filter can not filter the text accuratly.
For example, user can fill "length($match) > 3" in this entry, then all the words with less then 4 characters will not be replaced.
The syntax of this Filter using "Perl Expression" and following types of element can be used in this Entry:
If the expression result is "True", the text will be replaced, else it will not be replaced.
Note that the match sequence No. will be increased by one no matter Condition check result is "True" or "False".
It doesn't matter if you don't know Perl, there are a lot of easy templates and examples to use.