。
You can't recommend him too much.
Literal
She [topic-は] him [object-を] no-matter-how-much-いくら recommend even-if-ても too-much-doing thing [contrast-は] doesn't-exist.
A specialized rhetorical pattern: いくら~してもし過ぎることはない ('no matter how much you do X, you can't do too much') = 'one cannot X enough.' The structure stacks いくら~ても (concessive 'no matter how much') + ~し過ぎる ('do too much') + ~ことはない ('it doesn't happen, there's no such thing'). Together they assert the impossibility of overdoing the action — high praise. 推薦する ('recommend') here, but the pattern works with any verb where you want to emphasize there's no upper limit (注意してもしすぎることはない, 'can't be too careful').