Numbers 24:20

[Bil’am] Saw Amalek. He gazed at Amalek’s punishment.

Amalek was the first among nations. He preceded them all in waging war against Israel. This, too, is Targum’s [Onkelos] interpretation. And his end. Will be to perish by their hand, as it is said, “you shall obliterate the memory of Amalek.”

And he looked on the house of Amalek, and took up the parable of his prophecy, and said: The first of the nations who made war with the house of Israel were those of the house of Amalek; and they at last, in the days of the King Meshiha, with all the children of the east, will make war against Israel; but all of them together will have eternal destruction in their end.

VAYAR’ (AND HE SAW) AMALEK. “He contemplated the punishment of Amalek and he said, Amalek was the first of the nations — he was the first of them all to wage war against Israel. And so did Onkelos translate it. But his end will be to be destroyed by their hands, [as it is said], thou shalt blot out the remembrance of Amalek.” This is Rashi’s language.
It is possible that the word vayar is to be understood in its literal meaning [“and he saw,” and not, as Rashi explained it, “and he contemplated”], since Balaam was on the top of Peor, that looketh down upon the desert and so he looked towards the land of Amalek who dwelt in that hill-country., 14:45. Thus he said that Amalek is now ‘the first’ of the nations, meaning that he is considered a leader of the nations, because they were mighty men, and valiant men for the war; for were it not so, it would not have occurred to them to come and attack Israel, and Moses would not have had to choose a select number of men [to fight them], or to pray and lift up his hands [towards heaven] until he was weakened., Verses 11-12. He [Moses] also built an altar and called its name ‘Ado-nai nissi’ (the Eternal is my banner),, Verse 15. because he considered [the defeat of Amalek] a great miracle. Therefore this [man Balaam] said that Amalek is the first of the nations, but his end shall come to destruction more than all the others, as He said, For I will utterly blot out the remembrance of Amalek from under heaven., Verse 14. Similarly, ‘the first’ oils means “the best” of them, which are counted first [in quality]. The same [usage is also found in these expressions]: ‘the first’ [i.e., “the best”] of the devoted things; ‘head’ and chief over them;. ‘the chief’ spices. See Ramban, Vol. II, p. 528.

וירא את עמלק, from a location where these people were visible he beheld them.

ראשית גויים, as per Onkelos, i.e. the first organised nation militarily opposing the Jewish nation.

וירא את עמלק, “he saw Amalek” (in a prophetic vision). Bileam is also described as seeing the Kenite, the descendants of Yitro in our verse, also a prophetic vision. These two nations are lumped together here because the Amalekites were the first anti Jewish nation, whereas the descendants of Yitro, the Kenites were the first pro Jewish nation. This is why Bileam predicts total destruction for Amalek, and lofty dwellings for the Kenites. The word שים here is not an imperative mode of the root שום, “to place, to set,” but is a noun meaning: “the place of, the seat of.” They will dwell on rocks, i.e. secure from attack from below