请帮我看一下我这句中译英写得对吗?Now there are two time slots for you to choose from.中文背景：现在有二个时间段供你选择.

allennewton的对

Your translation was good. You can definitely say "two time slots" for 二个时间段
"..... for you to choose from." is correct. You can find such example from one of the Oxford dictionaries. Many people use it in conversation.
A more formal expression in writing will be:
Now there are two time slots from which you can choose.
I also heard people said, ".....for you to choose." I think either way is acceptable in daily conversation.
I would say that time span often refers to something that lasts or an extended period of time. I would not associate time span in a context of "二个时间段供你选择".
Just my two cents for you guys to consider.

应该是： 现在有两个时段供您选择。

翻译的很好啊！赞一个
哦，allennewton说的是对的

建议：Now there are two time spans for you to choose.
1.一般说时间段,用span,表示一段时间、持续时间,时间阶段（时间跨度）
2.choose足矣,无需加from
供参.