。
She prepares healthy meals for her family.
Literal
She [topic-は] family [for-のために] healthy good meal [object-を] prepares.
健康によい literally 'good for health' is a near-fixed adjectival phrase: な-adjective 健康 ('health') + に + the i-adjective よい ('good') = 'healthy, good for one's health.' It modifies 食事 ('meal'). The plain non-past 準備する is habitual ('prepares regularly'), not a one-time action — a typical case of Japanese using non-past for general truths about someone's behavior. The whole sentence reads as a brief domestic snapshot.