。
She gets along well with all of her classmates.
Literal
She [topic-は] classmate everyone [with-と] is-on-good-terms.
仲良くする ('get along well, be on friendly terms') uses 仲 ('relations, the space between people') in an evaluative compound with 良い ('good') — '[do things] in a way that makes the relations good.' The verb is reciprocal in feel and pairs naturally with と ('with') for the other party. みんな ('everyone, all') is appositive to クラスメート ('classmates'), narrowing down 'with classmates' to 'with all my classmates.' The ~ている form expresses the ongoing state of getting along — not a momentary action but a continuing habit of harmony.