On the threshold of his public life Jesus performs his first sign – at his mother’s request – during a wedding feast (cf. Jn 2:1-11). (CCC 1613)
From Catechism of the Catholic Church, Second Edition
“At Cana in Galilee there is shown only one concrete aspect of human need, apparently a small one of little importance (“They have no wine”). But it has a symbolic value: this coming to the aid of human needs means, at the same time, bringing those needs within the radius of Christ’s messianic mission and salvific power. . . . Mary places herself between her Son and mankind in the reality of their wants, needs and sufferings.”
St. John Paul II
And the third day there was a marriage in Cana of Galilee; and the mother of Jesus was there: And both Jesus was called, and his disciples, to the marriage. And when they wanted wine, the mother of Jesus saith unto him, They have no wine. Jesus saith unto her, Woman, what have I to do with thee? mine hour is not yet come. His mother saith unto the servants, Whatsoever he saith unto you, do it. And there were set there six waterpots of stone, after the manner of the purifying of the Jews, containing two or three firkins apiece. Jesus saith unto them, Fill the waterpots with water. And they filled them up to the brim. And he saith unto them, Draw out now, and bear unto the governor of the feast. And they bare it. When the ruler of the feast had tasted the water that was made wine, and knew not whence it was: (but the servants which drew the water knew;) the governor of the feast called the bridegroom, And saith unto him, Every man at the beginning doth set forth good wine; and when men have well drunk, then that which is worse: but thou hast kept the good wine until now. This beginning of miracles did Jesus in Cana of Galilee, and manifested forth his glory; and his disciples believed on him.