A signal is an automatic content feed you set up to track specific people, #hashtags, or $cashtags.
To create a new signal, click + in the top left of the screen and choose Signal. Add the people and keywords you wish to track and click Create (Figure 1):
Figure 1 Create a Signal
Any time these names or terms are used in chat, you will receive a notification in your left nav under Signals. Click the chat name to go to the original message where the keyword appeared (Figure 2):
Figure 2 Signals feed