"The churches in the province of Asia send you greetings. Aquila and Priscilla greet you warmly in the Lord, and so does the church that meets at their house." NIV translation
The "province of Asia" speaks of what is the western part of the modern day country of Turkey. Priscilla & Aquila had helped Paul to start the church in Corinth but were now with Paul in Ephesus where a body of believers was meeting in their home.
"All the brothers and sisters here send you greetings. Greet one another with a holy kiss." NIV translation
The "holy kiss" is also known as the kiss of peace and is still a part of the culture in that part of the world. Paul urges them to greet each other with a kiss on the cheek which expressed brotherly love and unity. This was especially significant when the Jewish believers kissed Gentile believers.
"I, Paul, write this greeting in my own hand." NIV translation
Up to this point, Paul had dictated the letter to someone else. He did this because he had problems with his eyes and it was very difficult and time consuming for him to write. He writes the final greetings so that there would be no doubt that the letter was authentic.
"If anyone does not love the Lord, let that person be cursed! Come, Lord! The grace of the Lord Jesus be with you. My love to all of you in Christ Jesus. Amen." NIV translation
Paul makes a very clear distinction between the believers and those who reject Jesus. It might sound tough but he is in fact saying that those who reject Jesus already stand cursed and He could come back at any time. He ends the letter by assuring the church of his love for them even though he has had to send such a corrective letter to them.