Reply lets you create and use smart filters to filter prospects based on different parameters.
To create a new custom filter, open the People page and click the Create new filter button.
Select the required property, condition, and click Apply to apply the filter or Save to apply and save the filter.
If you have saved a filter, you can use it later by clicking the Saved filters button and selecting the filter.
You can also create complex custom filters with several conditions - learn how to do this by checking this article.