Private repository
A repository only its owner and invited people can see. Nearly all company code is private.
What it tells you about a developer
Private work explains why a strong developer’s best code cannot be read from outside, and it does not stand in for public work. A quiet public profile leaves less to read, and a strong candidate can usually describe or demo the private work behind it.
Private repositories are invisible to everyone else, including recruiters. Most employed developers do the large majority of their work in one, because the code written for an employer belongs to that employer. A public profile is a separate sample: the part of their work a developer chose to build or publish themselves.