The name Xuan exists in both Vietnamese and Chinese (putonghua) language, but they have different pronunciation and different meaning.
Xuan in Vietnamese is almost certainly “Xuân”, a popular first name which means “spring” in English. The Chinese equivalent is 春 in Chinese (pinyin: chun).
Xuan, in pinyin, can be 宣 (meaning: proclaim/declare), a Chinese last name which has an equivalent in Vietnamese: Tuyên. There are other Chinese names that are also spelled as “xuan” in pinyin. For example, 玄 (meaning: profound/mysterious), which has a Vietnamese equivalent “Huyền”, a popular female first name, often combined with Diệu (Chinese: 妙, miao) to mean “wonderful”.