If you are asking how to spell it in Arabic, then Robert is روبرت Kathy is كاثي Twins are توأمان Otherwise, Kathy and Robert are pronounced the same, and twins is pronounced TAWA'AM.
It will depend on what dialect you're speaking:
Iraqi: "ma arif arabee"
Literally: "I don't know Arabic."
Syrian: "ma barif ahki arabee"
Literally: "I don't know how to speak Arabic."
Modern...