Paul begins now his final greetings by telling the Colossians about Tychicus and why he is sending him to Colossae(7). Paul is sending him along with Onesimus (Philemon's run away slave who became Paul's child in prison--Philemon 8-17). Paul wants the Colossians to be informed about how he is doing and to encourage their hearts (8-9). "That" in v. 8 makes this purpose explicit. In verses 10-11 Paul sends greetings from several Jewish believers (men of the circumcision, 11b) whom he describes as his "fellow workers for the Kingdom". They have been a comfort to Paul most likely by attending to him in his imprisonment in Rome (notice in Acts 28:how freely Paul could receive visitors during his Roman imprisonment).
Τὰ κατʼ ἐμὲ πάντα γνωρίσει ὑμῖν Τύχικος
Tychicus will tell you all about my activities.
ὁ ἀγαπητὸς ἀδελφὸς καὶ πιστὸς διάκονος καὶ σύνδουλος ἐν κυρίῳ,
He is a beloved brother and faithful minister and fellow servant in the Lord.
ὃν ἔπεμψα πρὸς ὑμᾶς εἰς αὐτὸ τοῦτο,
I have sent him to you for this very purpose,
ἵνα γνῶτε τὰ περὶ ἡμῶν
that you may know how we are
καὶ παρακαλέσῃ τὰς καρδίας ὑμῶν,
and that he may encourage your hearts,
σὺν Ὀνησίμῳ τῷ πιστῷ καὶ ἀγαπητῷ ἀδελφῷ, ὅς ἐστιν ἐξ ὑμῶν•
and with him Onesimus, our faithful and beloved brother, who is one of you.
πάντα ὑμῖν γνωρίσουσιν τὰ ὧδε.
They will tell you of everything that has taken place here.
Ἀσπάζεται ὑμᾶς Ἀρίσταρχος ὁ συναιχμάλωτός μου
Aristarchus my fellow prisoner greets you,
καὶ Μᾶρκος ὁ ἀνεψιὸς Βαρναβᾶ
and Mark the cousin of Barnabas (greets you)
(περὶ οὗ ἐλάβετε ἐντολάς,
(Mark is the one concerning whom you have received instructions—
ἐὰν ἔλθῃ πρὸς ὑμᾶς,
if he comes to you,
then welcome him),
καὶ Ἰησοῦς ὁ λεγόμενος Ἰοῦστος,
and Jesus who is called Justus.
οἱ ὄντες ἐκ περιτομῆς, οὗτοι μόνοι συνεργοὶ εἰς τὴν βασιλείαν τοῦ θεοῦ,
These are the only men of the circumcision among my fellow workers for the kingdom of God,
οἵτινες ἐγενήθησάν μοι παρηγορία.
and they have been a comfort to me.