Your name on an ESTA application should be entered exactly as it appears on your passport.
When entering your ESTA full name, it is important to check that the spelling, order, and spacing of your surname and given name match your passport details exactly.
If your passport shows only one name, that name is generally entered in the Surname field, and FNU, meaning First Name Unknown, is entered in the Given Name field.
Please review your passport details carefully before submitting the application, and apply for ESTA before your departure.