It runs 15 times. So, yes, that means that the first time through the loop i=0. Second time i=1. and so on. The loop condition runs for i=0 up to i<15 which means 0 to 14...which is 15 things.
A common pattern in programming is to start counting with 0 rather than 1. This means you often see things like: for( i=0; i<15; i++) and you learn to read that as a loop that runs 15 times.