That depends on what you want to match around what you want. Matching the word Result and the colon and quotes, and assuming there's nothing else,
let x = 'Result: "/tmp/abcd/1234"'
let y = substitute(x, 'Result: "\(.*\)"', '\1', '')
is one way to do it. Add .* to the beginning or end or both if there's characters to ignore there.
Regards, John Little