, it's as if they are in a completely different universe to them. You don't know what they are thinking or feeling and you have no idea how to convey things to them. Like you do with a young child, everything has to be done via sign language. This is ok to get across basic things but two adults can't really communicate like this.
Such being the case, don't be afraid to put in the effort to learn another language. Learning languages isn't easy. There are people who have been speaking their mother tongue their whole life who haven't truly mastered all the rules of grammar and the like. So it can be a frustrating process when you are learning another language and have to put up with all of the exceptions to the rules.
When you are young and speaking that language, you just pick the exceptions up. Soon enough you just implement them as if that is the case but you wouldn't be able to explain to someone why it is if they asked you. That is just the way it is and this can be annoying for a person trying to master a new language. No one said it is easy but it is worth it.
Let's say you meet someone for Israel and fall in love with them. Wouldn't it be great to learn how to speak Hebrew and speak to them in their mother tongue? If you learn Hebrew you can also speak to his or her family who maybe don't know any English. Again this isn't easy but in the long run it would be incredibly beneficial. You will have a relationship with them that otherwise you never would have. Even if you don't master it, the most important thing is that you tried and made the effort.
Learning another language is also useful when it comes to studying things that originally were published in another language. For instance if you are an Opera singer and singing in Italian or Spanish, there is no way your performance won't be improved if you learn Italian or Spanish and understand what you are singing about. Now you can perform and sing with real feelings.
The same can be applied to acting. For his role as the young Vito Corleone in The Godfather Part II, Robert de Niro performed the role in Italian. Of course it helped that he was of an Italian background but it was testament to the way he threw himself into the role. He was rewarded for his efforts with the Academy Award for the Best Supporting Actor.
Of course you can always do the reverse and teach people the language that you are well-versed in. You can help them overcome their language barrier. Many people go and travel to far flung corners of the world in order to do this. This is a very rewarding experience and one you will be very proud of.