Bedeutung von “only” — Learner’s Dictionary

only

adjective [ always before noun ] us uk /ˈəʊnli/
Doctors say his only hope is a transplant.You're the only person I know here.For many cancer patients, surgery is the only recourse.Smoking is his only vice.Are humans the only animals to use language?

A1 used to mean that there are not any others:

This could be our only chance.
You're the only person here I know.

(Definition von “only adjective” aus dem Cambridge Learner's Dictionary © Cambridge University Press)