intlangu: common reedbuck
Nansti intlangu: here is the reedbuck
Certainly not all, but at least the majority and most common nouns in isixhosa begin with the prefix 'i'.
This is partly because many modern words are Xhosified English (or Xhonglish)
iKhabathi: a cupboard
It is not a good rule to stick to just to put 'i' on the front of everything, but while you're learning people at least understand that your talking about a 'thing'.
Nantsi (here is the..) can be used for many things.
Nantsi indoda: here is the man, like in the Miriam Makeba song:
nantsi indoda emnyama verwoerd : Here is the black man, Vervoerd
or, in the opening of the lion king theme song
Nantsi ingonyama: here is the lion