If you ever play with swings you would already have experience resonance. You sit in the swing and start kicking your legs at a frequency (rate) close the natural frequency of the swing and the swing will eventually reach a maximum amplitude. You have just transferred lots of energy (max) to the oscillating system ( the swing).
When I walk there is some sort of rhythm which provides a driving force to the earings which I may be wearing. If the earings are dangling it would have a natural frequency . When the driving frequency approaches the natural frequency (tend to happen when I walk fast) of the earings they swing at a large amplitude. I have just transferred some of my energy to the earings !
