“不懂规矩的年轻人”可以翻译为 "a young person who doesn't know the rules" 或 "a youngster who lacks discipline"。
具体解释如下：
1、 "a young person who doesn't know the rules"：
直译了“不懂规矩的年轻人”，其中“who doesn't know the rules”明确指出了年轻人不懂规矩的特点。
2、 "a youngster who lacks discipline"：
“youngster”意为“年轻人”，与“young person”意思相近。
“lacks discipline”表示“缺乏纪律性”或“不懂规矩”，这里用“discipline”来概括“规矩”的含义，因为“规矩”往往与遵守纪律、行为规范相关。