LONDON—The term “metaverse” seems to be everywhere. Facebook is hiring thousands of engineers in Europe to work on it, while video game companies are outlining their long-term visions for what some consider the next big thing online. The metaverse, which could spring up again when Facebook releases earnings Monday, is the latest buzzword to capture the tech industry’s imagination. It could be the future, or it could be the latest grandiose vision by Facebook CEO Mark Zuckerberg that doesn’t turn out as expected or isn’t widely adopted for years—if at all. Plus, many have concerns about a new online world tied to a social media giant that could get access to even more personal data and is accused of failing to stop harmful content. Here’s what this online world is all about: What Is the Metaverse? Think of it as the Internet brought to life, or at least rendered in …