Ted's much braver than I am at giving new languages a go.
【翻译】在尝试学习新的语言方面，泰德比我勇敢得多。

And whenever he fails , he rolls with either Spanish or English with a different accent.
roll 的本义是：发出持续的声音。在本句是比喻用法，比喻 “（话语）滔滔不绝”。
【翻译】这句话的含义是：当他用不同的口音，滔滔不绝地说西班牙语或英语时，这意味着他没学好新的语言。

It's amazing how much you take language for granted until you can't understand it any more.
how much 引导主语从句，在这里等于 that：

It's amazing that you take language for granted until you can't understand it any more.
【翻译】令人惊讶的是，你对语言的理解自以为是，结果你再也听不懂。