The search field in a ListView will search all selected fields for the parameter entered.
So if you have attribute A and B selected for the search field and the user enters xyz in the search bar all records are retrieved where A OR B contains xyz.
If you want to perform a search more specifically, e.g. search where A contains xyz and B contains ZZZ then maybe the Grid-Search widgets might help you out, see:
https://appstore.home.mendix.com/link/app/49364/Mendix/Grid-Search