It could also be: "(Questa è) tua nonna, (questa è) la tua sorellina!". It depends from the context, as you can read below in IanMegill2's explanation. <Efylove>
За последен път се одобри от Efylove - 11 Февруари 2010 17:54
Hi Efy,
It means
(This is) your grandmother, (and this) is your little sister!
(For example, pointing at the people or their pictures or something...) As the grammar is non-standard, spoken Japanese, there is no usual "and" between the two people.
(But why there would be an exclamation point at the end here is something I don't understand...) Anyway, it is also not impossible that it could mean:
Your grandmother (with the usual grammatical subject marker "wa" elided in spoken speech) is your little sister!
This of course would be very strange, but it would help explain the presence of the "!" at the end... That's the "problem" with the Japanese language: it is heavily context-dependent, and the words above, by themselves, could mean either of the above two sentences...
Hi again Efy,
You didn't check your "Notifications" box under the message you sent me, so my answer above won't automatically be sent to you: I'll CC you, to make sure you get my reply.