undertake的含义很多，比如从事；承担；保证；负责等等，但在法律文件中，通常有两层含义：

(1) 承担；如undertake responsibilities等

(2) 保证；

1.承担：

On its part, XXXX wishes to inform you that upon full execution of this letter by all parties, XXX Beijing will be excited and honored to undertake all of ZZZ China’s rights and obligations under the Contract (including any exhibits or appendices to theextent applicable) and the YYY solely as they relate to the Contract, and willcontinue to serve you based on the same terms and conditions set forth in theContract and the related portions of the YYY.

XXX希望告知您，在所有相关方签署本函之后，XXX北京将兴奋并荣幸地承担ZZZ中国根据合同(包括任何适用的附录或附件)和YYY涉及合同部分享有的全部权利和义务，并将继续根据合同和YYY相关部分中相同的条款和条件为您服务。

2.保证：

甲方应保证办理电子支付业务账户的支付能力，并严格遵守支付结算业务的相关法律法规。

Party A shall undertake that it has the payment capability to conductelectronic payment business account, and it shall strictly comply withapplicable laws and regulations relating to payment and settlement business.