"Rwy'n hoffi chi. Dych chi eisiau mynd i'r caffi gyda mi am baned o goffi?"
=
"I like you. Do you want to go to the café with me to have a cup of coffee?"
I'm still learning Welsh, so this might contain mistakes, but it's better than saying you don't understand her... For future reference, you know.
Edit: Meant to reply to the comment below me.
I can't be arsed to write the pronunciation in IPA. Just go on Google Translate to hear how it's pronounced or learn Welsh on Duolingo.
Da iawn, rwyt ti'n gallu siarad / ysgrifennu Cymraeg nawr / rŵan! :)