You sometimes see people listening to music while riding their bicycle, but it's dangerous.
There are people who ride their bicycle and listen to music at the same time, but it's not safe.
ーYou sometimes see people listening to music while riding their bicycle, but it's dangerous.
「自転車に乗りながら音楽を聴く人がいるけど、危険だよね。」
listen to music while riding their bicycle で「自転車に乗りながら音楽を聴く」
dangerous で「危険な・危ない」
ーThere are people who ride their bicycle and listen to music at the same time, but it's not safe.
「自転車に乗って、同時に音楽を聴く人がいるけど、危ないよね。」
ride their bicycle and listen to music at the same time で「自転車に乗って、同時に音楽を聴く」
it's not safe で「安全ではない」＝「危ない」
ご参考まで！
カナダ 
