Many parts of the plan will fully take effect in four years. But some take effect quickly. For example, in six months the new law will bar insurance companies from denying coverage to children with pre-existing health conditions. Adults with pre-existing conditions will be added in four years.

四年之内，该计划的许多部分都将全面生效。但是其中一些措施将很快生效。例如，六个月之内，新的法律将禁止保险公司拒绝为存在先天性疾病的儿童进行赔付。四年之内，患有先天性疾病的成年人也将纳入偿付范围。

Bar: to forbid or prevent somebody from doing something 禁止;阻止

The players are barred from drinking alcohol the night before a match. 运动员在参赛前夜不得喝酒.