Acts 2:18 New English Translation

¹⁸Even on my servants,^[a] both men and women,
I will pour out my Spirit in those days, and they will prophesy.^[b]

Acts 2:18 tn Grk “slaves.” Although this translation frequently renders δοῦλος (doulos) as “slave,” the connotation is often of one who has sold himself into slavery; in a spiritual sense, the idea is that of becoming a slave of God or of Jesus Christ voluntarily. The voluntary notion is conspicuous here; hence the translation “servants.” In any case, the word does not bear the connotation of a free individual serving another. BDAG notes that “‘servant’ for ‘slave’ is largely confined to Biblical transl. and early American times…in normal usage at the present time the two words are carefully distinguished” (BDAG 260 s.v.). One good translation is “bondservant” (sometimes found in the ASV for δοῦλος) in that it often indicates one who sells himself into slavery to another. But as this is archaic, few today understand its force.
Acts 2:18 sn The words and they will prophesy in Acts 2:18 are not quoted from Joel 2:29 at this point but are repeated from earlier in the quotation (Acts 2:17) for emphasis. Tongues speaking is described as prophecy, just like intelligible tongues are described in 1 Cor 14:26-33.

New English Translation (NET)