、。
It seems she didn't sleep well last night.
Literal
She [topic-は] last-night, very could-not-sleep [seems-ようです].
眠れる is the potential of 眠る ('to sleep') — Japanese has a dedicated potential form rather than relying on a modal like 'can.' Combined with the あまり~ない frame ('not very ~'), the clause says she couldn't sleep much. ~ようです closes the sentence with an evidential: the speaker is inferring her poor night from external clues (a tired face, a yawn) rather than asserting it as direct knowledge. Softer than らしい (which leans on hearsay) and more committed than でしょう (pure conjecture).