Deictic words rely on situational context to convey meaning, which isn't fixed and changes with circumstances. When I say 'over there', you only understand where if you see where I'm pointing.
Pro Tip 2/3
Point of Reference
The meaning of deictic words can shift depending on the speaker's location and time of speaking. 'This morning' meant something different when I mentioned it yesterday.
Pro Tip 3/3
Conversation Clues
Understanding deictic terms requires listening for clues within a conversation or text regarding time and place. If a story begins with 'back then', look for earlier mentions of time for clarity.