Anointing of the Sick
It is for someone who is seriously ill, or very old and already weak. It can also be received before a major surgery. It gives comfort, peace, and courage, and, if God wills, also healing of the body.
The sign
The priest anoints the sick person's forehead and hands with oil.
Who gives it
The priest.
How many times
It can be received again if the person becomes seriously ill again, or if the same illness gets worse.
What the Bible says
James 5:14-15
14Is any man sick among you? Let him bring in the priests of the church, and let them pray over him, anointing him with oil in the name of the Lord. 15And the prayer of faith shall save the sick man: and the Lord shall raise him up: and if he be in sins, they shall be forgiven him.
Douay-Rheims Bible (Challoner revision), public domain.
Source: Catechism 1499, 1513-1516, and 1520