What does it mean to have a slow heart beat? Will you someday need a pacemaker?

See earlier answers. In your age group it is unlikely to be pathological, the most common pathology leading to a slow heart rate in your age group is hypothyroidism, but probably even more commonly, low heart rate is encountered because the person is conditioned. Predicting a future need for pacemaker because a person has a low heart rate when young is not based on any reliable data, unless pathologic to begin with.
Athletic condition. Slow hr could be due to physical conditioning. Agree that cannot predict future need pacemaker based on resting heart rate.