Jesus expected of everyone who wants Him to be their Saviour and Lord to be Making disciples. It should be possible for each follower to have (a minimum of) 3 disciples. And these disciples should each have their own 3 disciples – and the pattern continues. Every disciple of Jesus having their own 3 disciples.
If each disciples has their 3, then before too long there will be many, many disciples. It is an easy and good way to obey Jesus and multiply what is being done. Have your 3 disciples and help them to disciple 3 more of their own.
Chuck Wood has made some videos that are on YouTube that explain this in more depth. There is an introduction video to 1-3-9 and one about Finding a Timothy (someone who you can disciple).
In the same way, a church would grow significantly if each of the people each had 3 disciples. More often than not, the job of discipling is done by the pastor/s or paid staff, instead of each disciple having their own disciples.