A 'go around' is the term for: On approach to landing, when the pilot in command decides that to actually land would be dangerous - for any reason. For example, there might be a sudden high wind from an acute angle, or heavy rain is advised by the tower. The decision to not land may be taken from some distance away or perhaps ten seconds before touch down, the reason is always safety.
Whilst it may seem safest to be on the ground, one of the most usual reasons for a go around is if an aircraft that is landing ahead of you does not clear off the active runway in the time that it was expected. This compels the following a/c to go around. Equally, if a departing aircraft decides to abort their take off - then they will still be on the runway and the next approaching a/c must go around.
It is not a decision taken lightly but it happens all around the world all the time. If it happens to you, it means the folks at the front spotted the trouble in time! I have been paxing for 45 years and never had a go around.