What do "dasa," "das," and "dasi" mean? Is it a surname?

Complexity: 
Easy

"Dasa" is not exactly a surname. . .it's more of a modifier. "Ekendra" is Sanskrit for the One (Eka-) Lord (-indra), and "dasa" is Sanskrit for "servant of." So at the time of initiation (similar to confirmation—a name giving ceremony) we all get a name of God with "dasa" at the end, lest we forget who we are (servants of God).