In the last days (en tais eschatais hēmerais). Joel does not have precisely these words, but he defines “those days” as being “the day of the Lord” (cf. Isa 2:2; Mic 4:1).
I will pour forth (ekcheō). Future active indicative of ekcheō. This future like edomai and piomai is without tense sign, probably like the present in the futuristic sense (Robertson, Grammar, p. 354). Westcott and Hort put a different accent on the future, but the old Greek had no accent. The old Greek had ekcheusō. This verb means to pour out.
Of my Spirit (apo tou pneumatos). This use of apo (of) is either because of the variety in the manifestations of the Spirit (1 Corinthians 12) or because the Spirit in his entirety remains with God (Holtzmann, Wendt). But the Hebrew has it: “I will pour out my Spirit” without the partitive idea in the lxx.
And your daughters (kai hai thugateres hūmōn). Anna is called a prophetess in Luk 2:36 and the daughters of Philip prophesy (Act 21:9) and Act 2:18(handmaidens). See also 1Co 11:5 (prophētousa).
Visions (horaseis). Late word for the more common horama, both from horaō, to see. In Rev 4:3 it means appearance, but in Rev 9:17 as here an ecstatic revelation or vision.
Dream dreams (enupniois enupniasthēsontai). Shall dream with (instrumental case) dreams. First future passive of enupniaz from enupnios (en and hupnos, in sleep), a common late word. Only here in the N.T. (this from Joel as all these Act 2:17-21 are) and Jud 1:8.
Yea and (kai ge). Intensive particle ge added to kai (and), an emphatic addition (=Hebrew vegam).
Servants (doulous), handmaidens (doulas). Slaves, actual slaves of men. The humblest classes will receive the Spirit of God (cf. 1Co 1:26-31). But the word “prophesy” here is not in the lxx (or the Hebrew).