。
Your eyes give you away.
Literal
Eye [subject-が] lie [object-を] is-telling [emphatic-よ].
嘘をつく ('to tell a lie') is the verb collocation for lying — literally 'to attach/stick a lie' — with the eyes as the subject. The line personifies the speaker's eyes as the liars, a metaphor for 'the look in your eyes contradicts what you're saying.' The ~ている form marks the ongoing state of that lie being in place. Final よ as usual is an informative nudge to the listener.