Why mae'r rather than y?
The translation says 'the ... is' and yet there is no 'is' in the translation. If I was asked to translate this into Welsh I would have said 'Y llew eisiau bwyta cig'
What is the difference between mae'r and y in this instance?
Mae is part of the verb bod - 'to be'.
Mae e - 'he/it is
Mae'r llew... - 'the lion is...'. 'r is used instead of y or yr when it comes after a vowel.
Mae'r llew'n bwyta... - 'The lion eats/is eating...'
Mae'r llew eisiau... - 'The lion wants/needs/is wanting...' (yn/'n is not used with eisiau in sentences like this - it is an exception to the normal patterns)