Dashboard filter in Salesforce

A dashboard filter allows viewers to change the data visible on the dashboard by selecting a filter value from a drop-down list.

Note:
1. Maximum number of filters allowed per dashboard is 3 each with 10 values.
2. Fields will be available only from the reports in the filter drop-down.

Salesforce Lightning Dashboard with Filter:
 
 
Salesforce Classic:
To add filter, add "Add Filter" button


Sample filter: