This is from Cakes and Ale again.
The narrator has been told he is going to be invited to go to stay with a woman. He is not enthusiastic. The man he is talking to tells him your lines above. The meaning; "She has quite a good grass court" - she has a decent tennis court at her property. "And she does one very well.". You will be well looked after, with good food, comfort and company. This is quite idiomatic British English, and then really quite old. "Does one very well' would not be used in this way any more.