Based on the sentence in Filipino: "Ang pusa ko ay kakapanganak lang nang limang kuting." This translates to: "My cat just gave birth to five kittens." So your friend's cat had 5 new babies/kittens. A simple congratulations message could be: "Congratulations on the new arrivals! 5 adorable kittens, how exciting! Wishing you and your feline family all the best."