The Greek text states,
ἑκάστῳ δὲ δίδοται ἡ φανέρωσις τοῦ πνεύματος πρὸς τὸ συμφέρον
which is translated as,
but each man is given the manifestation of the Spirit «πρὸς τὸ συμφέρον».
The Greek word πρός is a preposition with various meanings. In this instance, it is followed by a present active participle in the neuter gender, singular number, and accusative case. Thayer states that this usage indicates "an intended end or purpose."
The participial phrase τὸ συμφέρον is functioning as a substantive (i.e., a noun). The lexical form is συμφέρω, which itself is formed from the combination of the preposition σύν, meaning "with," and the verb φέρω, meaning "to bring, bear, carry."
BDAG defines the verb συμφέρω as:
συμφέρω impf. συνέφερον; 1 aor. συνήνεγκα, ptc. συνενέγκας (Hom. [mid.]+; Aeschyl., Hdt.; ins, pap, LXX, Test12Patr; ApcEsdr 1:11 p. 25, 3 Tdf.; EpArist, Philo, Joseph.; Ath., 14:2 [mid.]).
① to bring together into a heap, bring together τὶ someth. (cp. X., An. 6, 4, 9; Jos., Bell. 5, 262, Ant. 16, 45) Ac 19:19.
② to be advantageous, help, confer a benefit, be profitable/useful (Hdt. et al.; Jos., Ant 1, 162)
ⓐ impers. συμφέρει τι someth. is good (for someone or someth.), someth. is useful or helpful 1 Cor 6:12; 10:23. οὐ συμφέρει μοι 2 Cor 12:1 v.l. (s. Windisch on this pass., which is prob. corrupt). συμφέρει τί τινι (Soph. et al.; Pr 19:10; Sir 30:19; 37:28 οὐ πάντα πᾶσιν συμφέρει) 2 Cor 8:10; IRo 5:3. συμφέρει τινί foll. by inf. (Epict. 2, 22, 20; Esth 3:8) GPt 11:48; ISm 7:1. συμφ. τινί foll. by ἵνα (B-D-F §393, 1; Rob. 992; POxy 1220, 19) Mt 5:29f (foll. by καὶ μή to denote, by way of contrast, what is not advantageous; here and elsewh. it is well translated it is better … than); Mt 18:6; J 11:50 (foll. by καὶ μή); 16:7. οὐ συμφέρει γαμῆσαι it is better not to marry Mt 19:10 (Polyaenus 3, 9, 2 διώκειν οὐ συμφέρει). W. acc. and inf. (s. EpArist 25) συμφέρει ἕνα ἄνθρωπον ἀποθανεῖν J 18:14.
ⓑ ptc. συμφέρων profitable, etc.
α. τὰ συμφέροντα what advances your best interests or what is good for you Ac 20:20 (Pla., Rep. 1, 341e; Philo; Jos., Bell. 2, 502, Vi. 370; 3 Macc 6:24).
β. σοὶ συμφέρον ἐστί w. inf. foll. Hs 7:5. οὐ συμφέρον (sc. ἐστίν) there is nothing to be gained by it 2 Cor 12:1 (cp. Thu. 3, 44, 2).
γ. subst. τὸ συμφέρον profit, advantage (Soph. et al.; ins; 2 Macc 11:15; 4 Macc 5:11; Philo; TestSol 7:2 D; Jos., Ant. 12, 54; 13, 152, τὸ αὐτοῦ σ. 14, 174. A common term, both sg. and pl. in ins in ref. to contributions to the public good by civic-minded pers., e.g. IPriene 119, 23 al.) τὸ ἐμαυτοῦ συμφέρον 1 Cor 10:33 v.l. τὸ κοινῇ συμφέρον the common good (cp. τὸ δημοσίᾳ συμφέρον POxy 1409, 11; Ocellus [II b.c.] 48 τὸ σ. τῷ κοινῷ) B 4:10. πρὸς τὸ συμφέρον (τινός) for (someone’s) advantage 1 Cor 7:35 v.l.; 12:7 (Aeneas Tact. 469; schol. on Pind., I. 1, 15b; cp. Jos., Ant. 15, 22). Also ἐπὶ τὸ συμφέρον Hb 12:10 (cp. Appian, Liby. 89 §420 ἐπὶ συμφέροντι κοινῷ, Syr. 41 §217; Jos., Bell. 1, 558 and Vi. 48 ἐπὶ συμφέροντι).—Schmidt, Syn. IV 162–72. M-M. TW.
It thus seems that the phrase πρὸς τὸ συμφέρον has an attested usage elsewhere in Greek literature, where it means "for (someone's) advantage," i.e. benefit (cp. 1 Cor. 7:35). Hence, the text means that the manifestation of the Spirit (i.e., spiritual gifts; cp. 1 Cor. 12:8-10) are given to each individual for his/ her benefit. Of course, Paulos then goes on to emphasize the necessity to show love for one another despite some in the Church having more prestigious (if you will) gifts of the Holy Spirit.