What is resonance?
Resonance means that your mind is tuned into the frequency of a thought, concept or emotion in the morphic field.
So when you encounter a situation that relates to that aspect, your vibrational response is aligned to fetch a certain set of responses based on the presence of that energy.
You've experienced this with an insight or aha moment, or a sudden mood change: your vibration was aligned with a frequency that then determined what you feel, and your responses and behaviors.
On a more complex level, you may resonate with fear, excitement and hope if you meet a new love interest.