OET interlinear NUM 6:18

uW Translation Notes:

Note 1 topic: figures-of-speech / possession

אֶת־רֹ֣אשׁ נִזְר֑⁠וֹ & אֶת־שְׂעַר֙ רֹ֣אשׁ נִזְר֔⁠וֹ

DOM head his_consecration_of,his & DOM hair_of head his_consecration_of,his

See how you translated the similar phrase in 6:9. The only difference here is that the second phrase makes hair explicit. Alternate translation: [the hair on his head that represents how he made himself separate … the hair on his head that represents how he made himself separate]

Note 2 topic: figures-of-speech / explicit

עַל־הָ⁠אֵ֔שׁ אֲשֶׁר־תַּ֖חַת

on/upon/above/on_account_of//he/it_went_in the,fire which/who below/instead_of

Yahweh assumes that readers will know that the fire was burning on the altar and that the peace offering was being sacrificed on that altar. You could say that explicitly if that would be helpful to your readers. Alternate translation: [the fire that burns on the altar under]

Note 3 topic: figures-of-speech / possession

זֶ֥בַח הַ⁠שְּׁלָמִֽים

sacrifice_of of,the_peace_offerings

See how you translated this phrase in 6:17.