It actually depends. A weak currency doesn't necessarily mean the country won't anymore engage in global trades. As a matter of fact, a weak currency could actually be designed on purpose. It could actually be intended by way of a policy to be used as a strategy in order to increase trades, exports in particular. In which case, since the currency is weak, exports are cheaper, making them more attractive for buyers compared to their competitors. Of course, there's also a need to balance since a weak currency would also mean imports are expensive.
But that's not really going to benefit the country in the long run, weak currency in global trades means that you've got a cheap export tariffs or something trade related but you're not really benefiting from it because you're paying a premium for those exports which is going to go to your local market much more expensive because you have to get some profits out of the payments that you've made in trades so in the end, the only one that's benefiting from this is the people that are on the outside of the country and not the people inside.