Have you ever noticed how some words in Spanish are almost the same as in English? Universidad means university, aire means air, and invitar means to invite. These words are called cognates, which are just 2 words in 2 languages that have a similar meaning, spelling and pronunciation. Basically, think of it as a word in a foreign language that you could probably figure out the meaning of without actually knowing the foreign language itself.
Cognates are really interesting because it can give linguists clues to how languages are related. An easy way to think about it is, the more cognates a language has with another, the closer it is to that language. For example, English and Japanese have little to no original cognates (they have some now, but only because of the mixing of the languages from industrialization and globalization). But, between English and Spanish, about 30-40% of all words in the languages are cognates for each other (“Using Cognates to Develop Comprehension in English“). That’s because of the European influence on the English language throughout history, and vice versa; for example, they gave us the word tornado, and we gave them picnic.
This is why they say that Spanish is one of the easiest languages for English speakers to learn–you already know almost half of the vocabulary from the start, and you don’t need to learn a new alphabet.
Most everyone has taken Spanish or French in high school, and even if you hated it, this is a real advantage to you. Along the same lines of English and Spanish, most languages are really just variations of a couple common languages; Spanish, for example, is a variation of Vulgar Latin (aka common-person Latin, not swearing). Think about it like this: a bunch of people started out in Western Europe, all speaking Vulgar Latin. They moved and migrated all over, eventually develop unique civilizations, and they subsequently alter their language a little. So, almost by default, languages in a specific family have very similar basic structures, because they’re all derived from the same language.
Take a look at some of the European language branches:
If you look at the Italic Language branch, you’ll find Latin. Follow it a little more, and you’ll find a cluster of 9 languages called the Romances (Romance, derived from Roman). A few of them are dialects–Catalan, for example, is a variation of Spanish that’s spoken in the Catalonian region of Spain. The core Romance languages of the list are French, Italian, Portuguese, Romanian, and Spanish; if you’ve taken any of these languages before, learning another in this family will be much easier, because you’ve seen something to it similar before. This can be applied to other branches of the tree; if you’ve studied Danish, you’ll have a lot easier of a time learning Swedish than, say Yiddish. And, based on the tree, you’ll have an even tougher time learning Ancient Greek.
So, if you took Spanish, the 4 easiest languages for you to learn are (in no order):
Ultimately, when you hear “easiest language to learn,” think “most similar to one you already know.”