。
She harbors ill will toward our group.
Literal
She [topic-は] our group [toward-に対して] malice [object-を] is-holding.
The compound particle ~に対して ('toward / against / with respect to') marks the target of an attitude or action — more formal and emphatic than plain に. Pairs naturally with stance verbs and emotion nouns: ~に対して悪意をもつ ('harbor ill will toward'), ~に対して責任を負う ('bear responsibility for'), ~に対して反対する ('oppose'). The progressive 持っている here describes a sustained state of holding the malice, not an instantaneous act. Note the loanword グループ — one of countless English-derived organizational terms (チーム, クラブ, メンバー) absorbed into modern Japanese.