What does the indwelling of the Holy Ghost enable the Church to do? The indwelling of the Holy Ghost enables the Church to teach, to sanctify, and to rule the faithful in the name of Christ.
But when he, the Spirit of truth, has come, he will teach you all the truth. For he will not speak on his own authority, but whatever he will hear he will speak, and the things that are to come he will declare to you. (John 16:13)
What is meant by teaching, sanctifying, and ruling in the name of Christ? By teaching, sanctifying, and ruling in the name of Christ is meant that the Church always does the will of its Divine Founder, who remains forever its invisible Head.
Further reading: CCC 871-873