It means that the author is a priest of the Congregation of the Holy Cross, a religious order in the Church:
from Wikipedia:
The Congregation of Holy Cross or Congregatio a Sancta Cruce (C.S.C.) is a Catholic congregation of priests and brothers founded in 1837 by Blessed Father Basil Anthony-Marie Moreau, CSC, in Le Mans, France.
A. A. [Milne] .
The initials LDN, put after a person's name, generally stand for Licensed Dietitian/Nutritionist.
It is the initials of the ring makers name
Royal academician.
N.kamalesh
professional engineer
Doctor of Medical Dentistry
It is the initials of the ring makers name
Certified Health Coach
The initials C.S.C. stood for Congregation of Holy Cross. Holy Cross is a Catholic religious congregation to which Father Ted Hesburgh belonged.
Not finding titular initials "PA;" prolly they mean Pennsylvania.
JS means your initials of your name and your wife name.