Introduced in Tiki6, this new feature allows mass search and replace of content in wiki pages, through "Admin home > Wiki > Tools > Mass search and replace" (tiki-search_replace.php)
It makes a revision on each page where replacements are done. The edit description is the localized version of "Mass search and replace".
It shows a list of checkboxes next previews of the change for you to select the changes you want to replace (or click select all - but the select all only affect those you can see on the screen limited by number you chose to see, with the usual pagination ). It changes one page at a time so if it times out perhaps it'll just stop and then you have to search again to find those that haven't been changed. You can manually reduce or increase the number of items i.e. checkboxes to show at a time depending on your need I suppose.
As a general old grandpa advise, you should try first a "mass replacement" on only one item before applying to the whole occurrence.
There is a bug with handling the ". Please read https://dev.tiki.org/item5456.