The phrase "this letter is from" is implied. Alternate translation: "This letter is from James, a servant of God and of the Lord Jesus Christ" (See: [[rc://en/ta/man/translate/figs-explicit]])
Possible meanings are 1) this is a synecdoche for Jewish Christians, or 2) this is a metaphor for all Christians. Alternate translation: "to God's faithful people" (See: [[rc://en/ta/man/translate/figs-synecdoche]] and [[rc://en/ta/man/translate/figs-metaphor]])
The term "dispersion" normally referred to the Jews who were scattered in other countries, away from their homeland Israel. This abstract noun can be expressed with a phrase with the verb "scattered." Alternate translation: "who are scattered around the world" or "who live in other countries" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])