。
She's in a bad mood.
Literal
She [topic-は] mood-tilted is.
ご機嫌斜め is a delightful set phrase: literally 'one's honorable mood is tilted/slanted,' meaning 'in a bad mood, cranky, out of sorts.' The opposite is ご機嫌 ('in a good mood'), without 斜め. Both phrases use the honorific ご prefix even for one's own mood, which gives them a slightly playful, mock-formal feel — the way English speakers might wryly say 'her ladyship is displeased.' Common in light, conversational descriptions of someone's grumpiness, often with affectionate or teasing intent rather than serious complaint.