Researcher visibility involves managing public information about you and your work in order to help raise your profile and promote your research.
The Open University's own Social Media Toolkit contains useful advice on getting started with social media and using it to increase your visibility.
There are many systems and tools you can use to manage and develop your online presence. Some will require you to sign-up and actively create a profile and others are automatically generated because, for example, you are a researcher at the University and publishing work. It’s worth knowing what tools are out there and how you can use them but by no means do you have to use them all. You may want to start by looking at researcher profile systems such as your OU people profile, ORCID, Google Scholar Citations, ResearchGate, and Academia.edu.