« N’être jamais sorti de son trou ».

Literal translation:
Never to have come out of one’s hole.

Meaning:
To have never been out of one’s own backyard.
To live in a cave.

Ça ne m’étonne pas du tout. Il n’aime pas voyager. Il n’est jamais sorti de son trou.
That doesn’t surprise me at all. He doesn’t like to travel. He’s never left his own backyard.