Basically, there are three points for our reflection today. The first is on the inevitability of scandals. Scandals are those actions or words which, literally, cause people to trip up and fall. Here they refer to words or actions which become obstacles preventing or making it more difficult for people to believe in and accept Christ and the Gospel. It is a terrible thing to come between a person and the call of Christ. The "little ones" can refer either to those who are young and innocent or those who are frail in their Christian faith. In this sense, parents and teachers can be a source of scandal to the young and innocent.
The second saying is about forgiveness and reconciliation and is not unconnected with the question of scandal above. If a brother (or a sister), that is, a fellow-Christian is clearly in the wrong, he should be corrected. And, if he clearly repents, then he is to be forgiven. The aim is not punishment but real healing and reconciliation. Remember the Prodigal Son.
The third saying is about faith, that is, deep trust in God. The apostles asked Jesus to increase their faith. This may be seen in the context of the warning about scandal and the requirement to forgive indefinitely. To forgive is not simply to write something off but to restore a situation of real harmony and inner peace between people.
You will shine in the world like bright stars because you are offering it the word of life.