We can't expect people to speak English everywhere in the world, it's not possible. When you learn the local language you will get less confused and it will be easier to seek help, you will also be able to adapt to your surroundings better, and you will be able to read signs, directions, labels, and warnings.
I am not saying you need to be fluent, I am saying that it is important to put a little effort to learn the basics of the local language. When I was living in Spain, I learned Spanish prior to going there and that helped me a lot, because people don't speak English in Spain, I was able to articulate myself and was good at understanding when people were speaking, and I got to practice my Spanish when I was there because I was speaking it all the time so I became fluent.
Before travelling somewhere, you need to know what the local language is and you need to learn the basics of it as well. You will look confident which is better that looking like a fool. Not convinced yet?
1. Locals appreciate it
Everyone loves when you show interest in them, and learning the local language is the best way to show that you care about the country and the locals. Even if you know a few basics language, it still shows that you care and locals will appreciate it and be more friendly with you and be happy to help. When people see that you are genuinely trying, they will be more than happy to help you find your way if you are lost, order the food you want, and they even might hang with you or invite you somewhere with them.
2. It will make your life easier
As I mentioned, if you are traveling to a country where people don't speak English, your travel experience will be hard and not enjoyable. You won't be able to navigate day to day activities such as going to restaurants and cafes, taking transportation, reading signs, and much more. If you go to a restaurant for example; you can't just point and hope, you need to understand the local language and be able to order specific food/meals. When it comes to transportation, knowing the basics of the local language will help you get on and off buses, taxis, metros, and trains, you need to be able to move from point A to point B. Most importantly, you need to be able to read signs or else you might get lost, and since sings are everywhere, they are extremely important.
3. You will experience the culture better
To better experience the culture, you need to speak the local language. When you learn stories about the culture, you get to learn what the country's priorities are, and then be able to understand the culture better. You can hear and think about a culture, but to experience it; you need to speak the local language.
4. You will meet new people
I have met a lot of people while traveling, and you probably have as well especially if you are a solo traveler. There are some amazing people around the world, but not all of them speak English. If you know the basics of the local language and know even a few sentences, you have given yourself the opportunity to meet new people and maybe make new friends. You will be able to speak to the taxi driver, make small talks if you're in a shop, get to know the person sitting next to you on a long bus drive, and much more. If you know the local language, the people you meet everyday might become your friends.
I know you might be thinking "Why should I learn a new language if I'm visiting the country once?". Here's the thing, there are some multi-national languages such as French, Spanish and Portuguese. You might visit Spain and then visit a lot of different countries in South America, or you might visit France and then visit Switzerland, Belgium, and countries in Africa. As a speaker of a foreign language, you are able to befriend a lot of people from around the world.
5. It is good for you
Learning a new language is generally good for you, it improves memory, strengthen the ability to solve problems, and enhances creativity. And as you develop these skills, your confidence will increase, and also this might help you when it comes to the business/work world. I speak multiple languages and I've only seen benefits from it.