“From Simon Peter” Your language may have a particular way of introducing the author of a letter. This could be translated as “I, Simon Peter, wrote this letter.”
## slave and apostle of Jesus Christ ##
Peter speaks of his attitude of being Jesus Christ's servant. He also was given the position and authority of being Christ's apostle.
## to those ##
Peter seems to be addressing all believers who may read this letter. Alternate translation: "to believers."