1. 两个；两个都
You use both when you are referring to two people or things and saying that something is true about each of them.
e.g. She cried out in fear and flung both arms up to protect her face...
她吓得大叫，并且抡起双臂护住了自己的脸。
e.g. Put both vegetables into a bowl and crush with a potato masher.
把这两样蔬菜都放进一个碗里，然后用捣土豆器把它们捣碎。
2. 不仅…而且…；…和…都；既…又…
You use the structure both...and when you are giving two facts or alternatives and emphasizing that each of them is true or possible.
both的翻译
e.g. Now women work both before and after having their children...
现在妇女在生孩子前后都要去工作。
e.g. Any such action would have to be approved by both American and Saudi leaders.
任何这样的行动都必须获得美国和沙特领导人双方的批准。