What does "Whatever you bind on earth willl be bound in heaven" mean?
See: Matthew 16:13-20; Matthew 18:15-20
The Gospel is the key to the kingdom of heaven (aka the kingdom of God). Mark 16:15,16
The apostles had the authority to establish congregations, appoint elders and when necessary to excommunicate unruly members. Paul, as an Apostle had the power given to him. 1 Corinthians 5:4,5;2 Corinthians 13:10; 1 Timothy 1:20
With the death of the apostles, gifts and authority by the Holy Spirit ceased. No one has the authority to "bind and loose" today.
I hope this helps,
God bless,
Glenn