The German verb is a compound verb: "vorkommen". It can be translated to "exist", "happen", "be found" or "occur". For instance, if someone was talking about earthquakes or weddings, he could refer to them in the plural.
@Julika : Please remove the hint given "to come", "to arrive" if they are not the best words for 'vorkommen'. Thank you!
Any idea what this actually means? I'm not sure what they mean by "They occur here often".