To proclaim the word of God to the assembly gathered for the celebration for the Mass.
Functions of the Lector
The Introductory Rites
In the procession to the altar, in the absence of a Deacon, the reader, wearing approved attire [see GIRM, no. 339], may carry the Book of the Gospels, slightly elevated. In that case, the reader walks in front of the Priest but otherwise walks along with the other ministers.
Upon reaching the altar, the reader makes a profound bow with the others [see also GIRM, no. 274]. If he is carrying the Book of the Gospels, he approaches the altar and places the Book of the Gospels upon it. Then the reader takes his own place in the sanctuary with the other ministers. (GIRM, nos. 194-195)
The Liturgy of the Word
The reader reads from the ambo the readings that precede the Gospel. In the absence of a psalmist, the reader may also proclaim the Responsorial Psalm after the First Reading.
In the absence of a Deacon, the reader, after the introduction by the Priest, may announce the intentions of the Universal Prayer from the ambo.
If there is no singing at the Entrance or at Communion and the antiphons given in the Missal are not recited by the faithful, the reader may read them at an appropriate time (cf. nos. 48, 87). (GIRM, nos. 196-198)
Source: The Lector at Mass | USCCB
Lectores: Alejandra Vizzani