To help find people in your organisation there is a People Directory which reads all the information from your organisations user accounts and provides an intuitive way to find people.
This is best started by either searching for the person you are looking for, or you can start to apply some filters.
The typical type of searches are based on a name, department, location or job title however if you are familiar with Delve, you can also search for any content from the users delve profile such as hobbies and interests or project experience.
To aid searching for people there is also a filtering option which can be turned on that allows users to filter by 'Department' or 'Location' depending on the information stored for users. Multiple options can be made to search across multiple areas.