"What is she like?"
Translation:Sut un yw hi?
un here is acting as a noun - 'a one'.
sut...? in front of a noun is best translated as 'what (is) ... like?', and it is followed by a soft mutation.
So instead of the literal 'how a one is she?' It renders into awkward English as 'What sort of a one is she?' or, better, 'What is she like?'. An example if where English and Welsh use very different patterns to convey the same meaning.
- Sut athro yw e? - What sort of teacher is he?, How is he as a teacher?, etc
- Sut ddyn ydy o? - What sort of man is he?
- Sut le yw Aber - What is Aber likeas a place?, What kind of a place is Aber?'
In comparison, Sut mae hi?, with the question refering to the verb mae, means simply 'How is she?', as in asking about how is her health/feeling.