。
You'll get scolded when mom gets home.
Literal
Mother [subject-が] came-home [when-たら] get-scolded よ.
しかられる is the passive of 叱る ('scold') — 叱る → 叱られる, following the godan passive pattern. In Japanese, the passive often maps English 'get [past participle]': 'get scolded,' 'get yelled at.' The subject of the passive (the scolded party) is omitted; context supplies 'you.' よ at the end is the warning/assertion particle.