Here the words "they" refer to Paul and Barnabas, and the word "We" includes Paul, Barnabas, and the disciples. The word "them" refers to the disciples. (See: [[rc://en/ta/man/jit/figs-exclusive]])
Here "souls" refers to the disciples. This emphasizes their inner thoughts and beliefs. Alternate translation: "Paul and Barnabas urged the believers to continue to believe the message about Jesus" or "Paul and Barnabas urged the believers to continue to grow strong in their relationship with Jesus (See: [[rc://en/ta/man/jit/figs-synecdoche]])
Some version translate this as an indirect quote, "saying that we must enter into the kingdom of God through many tribulations." The word "we" here includes Luke and the readers. (See: [[rc://en/ta/man/jit/writing-quotations]] and [[rc://en/ta/man/jit/figs-exclusive]])