Segments are a great way of managing your mentions.
First, you need to add the filters you want for your mentions. You can add as many filters combinations as you need.
Once you created the filters combination suitable for your segment, remember to save the segment. You also need to name the segment you've created.
All your segments will appear right under "Mentions" section, so you can easily access them anytime.
You can filter your analysis on the dashboard based on your segments.
You can also create reports on specific segments only.