Definition (Cambridge Dictionary):

1. used after an order or suggestion to show what the result will be if you do not follow that order or suggestion[否则，不然]

2. differently, or in another way[别样地，以另外的方式]

3. except for what has just been referred to[除此之外]

Example:

I'd better write it down, otherwise I'll forget it.

我最好把它写下来，否则我会忘了的。

Protestors were executed, jailed or otherwise persecuted.

抗议者被处决、监禁或受到其他方式的迫害。

I can't meet you on Tuesday - I'm otherwise engaged/occupied.

星期二我不能与你见面——我要忙别的事。

The bike needs a new wheel, but otherwise it's in good condition.

这辆自行车除了需要一个新轮子外，车况良好。

The poor sound quality ruined an otherwise beautiful film.

本来是一部优秀的电影，可是却被这糟糕的音质给毁了。