"'S e ur beatha, a sheanair."
Translation:You are welcome, grandfather.
The difference between do (thy, your) and ur (your, y’all’s) is the same as between thu and sibh – the first one is only singular and informal, the second is plural (used when you speak to more than one person) or singular formal (when you speak to someone with whom you are not on first name terms, a stranger or someone you want to show respect).
Thanks for explaining the difference between 'do' and 'ur' but whats the difference between beatha and bheatha? I think its masculine and feminine, but I just had this same sentence with 'bheatha' and 'boy' and this one is 'beatha' with 'grandfather'. Or do I have it all wrong? :D