"Watchman" is a Biblical concept of how the Lord appoints people to stand in a specific place or time guarding and in watchful alert. This Watchman place is therefore a very broad concept of spiritual engagement.
You can stand watch over a place or group that is very personal: your family, your community, your work place, your church.
You can stand watch over an organisation, the Church, an area of business or service, another nation or people group, international regions, or the Global.
Most Christians are called to act as a watchman in some capacity, but the way that they opperate will look different if they have a specific Watchman call. All are called to watch and pray, but some will carry a weight of authority and responsibility in their sphere that is their primary call.
The Pastoral Watchman
bringing warnings to the Church and world calling for righteousness (Ezekiel 33)
The Promise Holder
Reminding the Lord of His promises according to (Isaiah 62)
The Sentinel
Strategic watch from a long view, big perspective (Isaiah 21)
The Gatekeeper
First responder, position of guarding and gathering people to stand in the gap (Nehemiah 4)