Based on the message you shared, your friend is talking about someone else's (Lisa's) cat having babies - not her own babies! The German text says that Lisa shared on Instagram that her "Tatze" (which means "paw" - a cute nickname for a cat) had 3 babies (kittens). Your friend is expressing how cute they look and that she wants a cat too. So this isn't about congratulating your friend on her babies, but rather Lisa's cat had 3 kittens! Your friend is just sharing this news with excitement and some envy because she wants a cat herself.