go out... go in. Figure of speech Synecdoche (of Species), App-6, put for life in general, especially all official movements, and actions.
Related Commentaries of Numbers 27:17
Numbers 27:17
17 Which may go out before them, and which may go in before them, and which may lead them out, and which may bring them in; that the congregation of the LORD be not as sheep which have no shepherd.