What is Te agradezco mi Bella sobrina in English?

The most direct translation of "Te agradezco mi bella sobrina" is:

"Thank you, my beautiful niece."

However, depending on the context, you might use a more natural English phrase like:

* "Thank you, my lovely niece."

* "I appreciate you, my beautiful niece."

* "I'm grateful to you, my beautiful niece."