What is it? It's many things to many people. To those in the practice it's a spiritual dedication of thought; it's devoting their lives to God and to helping and healing people as Christ Jesus did. To others it's having a Christian Science practitioner you can call on when you need someone to pray for you, to help you become more spiritually enlightened, to heal you.
What kinds of things are healed? Sickness and disease of every type. Sin. Moral shortcomings. Dispositional hang-ups. Deep-seated fears and concerns. Hatred. Animosity. Criminal instincts. Unemployment. Lack. Limitations. The list is endless.
What kind of work is it? It's prayer. Understanding God better. Feeling and witnessing His love and care for His children. Isn't this what Jesus taught and lived, and urged his followers of all time to do?