I have a look on it and there are many beautiful art paintings there, I also easily find skilled artists with their paintings.
Other than that, I like its layout, logo and colors, I am not sure about its content because it is not in English but I am sure you did a great work there.
I really like the aesthetics of your website, the gentle colours that you used complete each other and the entire site is easy on the eye. I can't say much about the content, because I don't understand the language, but I really like the overall feel of BanTranh.
There is just one thing that I would maybe consider changing and that's the light orange colour just above the footer with the payment methods. It doesn't really go well with the light purple shade that you used before it - I think even the simplest white colour would look better there. But that's jut me nitpicking, your website is great on its own.
You're website looks pretty good, I like the art and different colors, I really enjoyed it, but I have one suggestion: You should consider making your website multilingual, which means it should have more languages, so all the visitors can understand. It will also help your reach. Good luck!