יָדִ֣ין בַּ֭גּוֹיִם מָלֵ֣א גְוִיּ֑וֹת מָ֥חַץ רֹ֝֗אשׁ עַל־אֶ֥רֶץ רַבָּֽה׃
Ia menghakimi bangsa-bangsa dengan timbunan mayat; Ia meremukkan kepala yang berkuasa atas negeri yang besar.
Or HaChaim
וחציו ימחע, "and smashes their arrows." We may best understand this by referring to Tanchuma Beshalach 15 where Isaiah 24,21 is explained. The author of the Midrash understands the words יפקד ה׳ על צבא המרום במרום that G'd does not annihilate the army of a nation in the terrestrial world until after He has vanquished that nation's "protector" in the celestial spheres. If the nation is only "weakened" and not destroyed in battle on earth, this is a sign that its שר, "protector or representative" at the celestial court has not been vanquished. G'd only humbled such a representative prior to this representative's "client" on earth suffering a defeat. When a nation experiences what happened to Sodom and Gomorrah, this meant that the celestial representatives of these kingdoms had been liquidated by G'd. Bileam refers to these celestial representatives of the various nations as "their arrows", the ones who carry on the fight on behalf of their clients in the celestial spheres. The word ימחץ may be understood as similar to Psalms 110,6: מחץ ראשו על ארץ רבה, "He crushed its head in the land which is "great" i.e. in the celestial spheres." It is a reference to the "protectors" of these various nations being vanquished. If we were to understand the word מחץ as meaning immersion or washing, then Bileam alludes to all these arrows as having been soaked in the blood of the enemies of the Jewish people.
Sforno
כבס ביין לבושו, the fourth sign identifying the Messiah is that he will be able to launder his garments in blood. He will have to do this as he will find many people who have been slain in the war preceding his coming, and he will assist in their burial. (compare Isaiah 63,2 מדוע אדום ללבושך “why are your garments so red?”) Another allusion to this is found in Psalms 110,6 ידין בגויים מלא גווית, “he works judgment on the nations piling up bodies.”
Rashbam
כאחד שבטי ישראל, describe this tribe’s warding off such attacks, similar to what Moses said in Deuteronomy 32,36 כי ידון ה' עמו, or in Deut. 32,43 דם עבדיו יקום ונקם ישיב לצריו. “He will avenge the blood of His people, for He will wreak vengeance on his foes.” David expresses similar feelings in Psalms 110,6 when he says:ידיו בגויים מחץ גוויות מחץ ראשו על ארץ רבה, ”He works judgment on the nations, heaping up bodies, crushing heads far and wide.”