The stranger elsewhere is one of another nation, here one of another tribe, one no Levite. That cometh nigh, so as to do the offices mentioned Numbers 1:50.
Related Commentaries of Numbers 1:51
Numbers 1:51
51 And when the tabernacle setteth forward, the Levites shall take it down: and when the tabernacle is to be pitched, the Levites shall set it up: and the stranger that cometh nigh shall be put to death.