One of customs practiced during Lent is the covering of the Cross and statues/images with purple cloths. This occurs during the last two weeks before Easter. In older days this time called Passiontide and started on Passion Sunday, which was the 5th sunday of the Lenten season. Passiontide would end on Good Friday. Some churches still celebrate Passiontide, but in the Catholic church the name is no longer used even though the tradition is still practiced.
There are a few ideas behind the covering of these objects during this time. The first is to take focus off of the churches ornamentation and to bring attention to the penitential season of Lent, focusing on the Passion of Christ only. The Cross is also covered and will be revealed again on Good Friday, to emphasize Christ bearing the Cross on that day. Another way the covering reminds us of the passion concerns the Gospel account of the curtain being torn in the Temple in Jerusalem at Christs death.
Mark 15:37-39 And Jesus, having cried out with a loud voice, gave up the ghost. And the veil of the temple was rent in two, from the top to the bottom. And the centurion who stood over against him, seeing that crying out in this manner he had given up the ghost said: Indeed this man was the son of God.