With over 1 million words and about 4,000 new ones added every year, English is a giant "word magnet." It grows so fast because it constantly borrows and steals cool words from every other culture on Earth!
If you feel like English is hard to learn because there are too many words for the same thing, you're right! English has an appetite for words unlike any other language.
According to the Global Language Monitor, English passed the 1,000,000 word mark years ago. For comparison, a typical English speaker only knows about 20,000 to 35,000 words.
English didn't get big by making up its own words; it got big by "kidnapping" words from other languages:
English is highly adaptable. It doesn't have a strict central body (like the Académie Française for French) to "police" the language. If people start using a slang word from the internet, it can become an official dictionary word in just a year or two.
English is a living, breathing history of global interaction. It is the largest vocabulary on Earth because it is a mix of almost every other language ever spoken.
