。
She's doing her homework right now.
Literal
She [topic-は] now homework [object-を] is-doing.
やる is the casual register's all-purpose verb for 'do,' often replacing する in everyday speech. 宿題をやる feels more like a kid talking about school than an adult listing tasks; 宿題をする is the slightly more neutral form, while ~する compounds remain the textbook standard. やる carries a faint extra connotation of effort or willingness — 'tackle, take on' — and turns up in expressions like やってみる ('try doing'), やる気 ('motivation').