Of course, we all understand that theoretically heads or tails can fall out with equal probability. However, heads can fall out in 100% of cases, as well as tails. I believe that such an event cannot be predicted with 100% certainty.
The more times you repeat the experiment, the closer the results get to 50/50. Have a look at the
law of large numbers. Each indivudal coin toss gives a random result, but those random results average closer and closer to 50% with each additional coin toss you make.
Of course in theory the outcome of an individual coin toss is pre-determined and dependent on spin speed and direction, air resistance, etc - but that's a separate issue.