Commentary for Numbers 2:20

ועליו — Understand this as the Targum does: and those who were close to him were the tribe of Manasseh.

As Targum translates “the one near him.” Previously (v. 5, 12) Rashi did not need to explain the word עליו (with him, lit. “above him”) because the Torah added the words “those who camp.” Thus it was obvious that the explanation is as Targum translates. However here where it does not add anything, but merely states “along with him is the tribe of Menashe,” I would not know the meaning of the word ועליו, therefore Rashi explains “as Targum translates.”