The manifest is the file the browser reads before anything runs. It is the contract, and the contract is why an extension can be reviewed before it is installed.
About 1 min of reading
Count the reach
Write the host list
Before you run it, say out loud what it will print. Then open the answer.
Attempt a star
Before you run it, say out loud what it will print. Then open the answer.
Refuse by name
Before you run it, say out loud what it will print. Then open the answer.
A star is a reach nobody can read. A list is a reach that a reviewer counts, and a count is a claim.
The host list. Wide is a reach that includes pages that were never asked about.
The hosts it may touch. A named reach is a reach that a reviewer can read.
The version is a number in the file. A number in the file is a number that a review can be about.
The refusal names the permission. A named permission is a permission that can be argued with.
Each one is defined here on this site. Open the entry for the full definition and the other words it points at.