Metaphor and simile a little bit resembling.People use these figures of speech to make their speech more colorful .
You're my heart, you're my soul
I keep it shining everywhere I go
You're my heart, you're my soul
I'll be holding you forever, stay with you together
The speaker is drawing a parallel between his beloved’s and his main organ. She doesn’t actually alike a heart or soul. But she is so importante for him just like heart.
You can also use metaphors and similes to help explain concepts that confuse your listener. First, identify the point you want to explain. Then find a topic your listener might know well where that point also comes up. Then use a comparison to link your point to the familiar topic to help your listener understand.(http://grammar.quickanddirtytips.com/grammar-similes-metaphors.aspx)