The vast majority of people with a hiatus hernia have little or no symptoms from it.
It is noted during an endoscopic examination for another symptom.

Symptoms attributable to a hiatus hernia include:

Excessive belching
Regurgitation
Acid relux

The diaphragm muscles surrounding the lower oesophagus and the fact that a portion of the oesophagus is within the abdomen contributes to the prevention of reflux.
This helps to explain the high proportion of patients with acid reflux having a hiatus hernia.
These patients may develop the complications of acid reflux (or GORD).

Rolling hiatus hernia may present with pain and vomiting. The portion of stomach protruding through the diaphragm may be damaged and even lose its blood supply (strangulation) in rare cases.
This is a surgical emergency and requires prompt treatment to save the stomach.