This ngram shows use of the word in British English:
This ngram shows use of the word in American English:
As you can see, it is used in both, but more so in British English.
American English speakers tend to use the word to mean that something is beautiful, or nice, particularly another person (for example "you look lovely" or "she is lovely"). British English speakers do the same but have a wider use of the term which includes using it in place of "beautiful" and extends to experiences in place of terms like "wonderful" and "delicious" (for example "we had a lovely time" or "that's a lovely cup of tea"). British speakers also use it sarcastically (for example "well that's just lovely!").