To lead the congregation in prayer to the Lord.
Intercessions should be around 5 mins long, and prayerfully prepared in advance.
The minister will usually be in touch during the week to give some help with specific things to pray for, including tying prayers into the theme of the passage/sermon/service.
Remember these are not simply personal prayers, but rather leading God's people in prayer. Therefore you will want to pray words that a congregation of faithful Christians can say 'Amen' easily, not being unsettled by controversial secondary topics. You will also want to use language people can easily understand and pray along with.
(You won't need to move the lectern microphone - volume etc can be adjusted from the sound desk)
Thank you for the wonderful work you do for the loving Lord Jesus Christ.