Sometimes missionaries and members of the Church of Jesus Christ of Latter-Day Saints use terms and phrases that can be hard to understand. Hopefully this should clear up any confusion. If you have questions, don't hesitate to ask!
AP: Assistant to the President. Two missionaries who help the Mission President with anything he may need.
BoM: The Book of Mormon.
Investigator: Someone who is meeting with the missionaries and learning about the gospel of Jesus Christ, the Book of Mormon, and the LDS Church.
LDS: Latter-Day Saint. This an abbreviation of the official name of our church: The Church of Jesus Christ of Latter-Day Saints.
Mission President: The man who oversees all missionary work and missionaries in a specific area.
MTC: Missionary Training Center. Before serving in their assigned area, missionaries are taught how to preach the gospel and speak their mission language.
PMG: Preach My Gospel. A book missionaries use to learn how and what to teach.
RM: Returned Missionary