Talking is much better than belligerent exchange that went before it.

【直译】和谈要比和谈前的交战好得多。

【意译】早和谈远远胜过交战之后再和谈。

that went before it：限制性定语从句，修饰belligerent exchange 。go 意为“出现；发生”，go before 意为“先于......发生”。

原句的意思，实际就是：

Talking is much better than belligerent exchange that took place before talking.