What is the meaning of sayid kharnain

Sayid is a common title used as first names, it simply means "master", "sir", "mister". Kharnain is another spelling of Qarnain, which means "two horns", and itself is a shortening of the word Dhul Qarnain, which means "two-horned one", which is the name of a king/general mentioned in the Quran in Surat al-Kahf.

You can use this name since it doesn't have a bad meaning, but it doesn't have a special meaning either. It simply means "Mister Two Horns". If Kharnain is a common name in your culture then it is fine to use it.