The redirect rule starts at the old path.
The rule starts at /old
The rule row and request row both name /old.
rule from=/old
The request path matches the rule
Because the request path matches the rule's from path, the redirect rule applies.
/old matches /old
The rule target is /new
The rule's to row gives the next path that the response should name.
rule to=/new
Summary
The redirect rule turns the old path into the new path.
rule selects next path