Based on the message, your friend is talking about Lisa's cat (Tatze) having 3 kittens (3 Junge). The message is in German and says something like "Omg!! Did you hear what Lisa shared on Instagram? Her cat had 3 kittens - they look sooo cute. I want a cat too :(((" So if you want to congratulate your friend, you'd be congratulating her on 3 new kittens. However, it seems the kittens actually belong to Lisa, not to the friend who sent you this message.