from international train to country train station

I assume you mean Francia (Franca) station.
It's about a 5 minute walk from there to the Barceloneta stop on the L4 metro line. Take that Metro to Verdaguer (direction Trinitat Nova), then transfer to the L5 line (direction Cornella Centre) and Sants station will be 4 stops along.

thanks norm,i did mean the franca station,we have a hour and 15 minutes to catch a connecting train ,should this be enough time thanks

You should be fine....providing your arrival is on time.