differrece between [geta] and [kunna]
what is the subtle differrece between [geta] and [kunna], when they both used in the meaning of [be able to]?

Question

Answer

Sometimes you know how to do something (kunna) but you can't do it... like: I know how to ride a bike (að kunna að hjóla) but maybe I fall and break my leg and then I can't ride a bike (get ekki hjólað) 
So you say:
 I'm able to: ég get 
and
I know how to: ég kann