Celebrities who are friendly and easy to talk to are often described as approachable. It means they are nice and open, so you can easily approach them and say hello.
A text is approachable if a reader feels like it's easy to understand and connect with. Approachable also describes how you approach, or get to a location. If your school is located deep in the woods, it might only be approachable by one road. In the winter, that road had better stay plowed or your school won't be approachable by anyone at all.