Matrimony
A man and a woman promise each other love and faithfulness for their whole life, and God unites their love.
The sign
The "I do" the bride and groom say to each other before God and the Church.
Who gives it
In the Latin Church, the bride and groom give the sacrament to each other. The priest or deacon receives their "I do" in the name of the Church and gives them the blessing.
How many times
It is for life.
What the Bible says
Matthew 19:6
Therefore now they are not two, but one flesh. What therefore God hath joined together, let no man put asunder.
Douay-Rheims Bible (Challoner revision), public domain.
Source: Catechism 1601, 1613, 1623, 1626-1627, 1630, and 1640