Okay, sweetie. You know how you speak English and it's your first language. Well, there are lots of other people in the world who speak different languages as their first language. But sometimes, they want to learn English because it's a really important language that is used all over the world.
Now, when these people learn to speak English, it's called "English as a foreign language" if they're learning it in a country where English is not the primary language. And it's called "English as a second language" if they're learning it in a country where English is the primary language (like America).
Learning a new language can be tricky, so these people might need to go to school to learn English. They might have a teacher who speaks both their language and English, so they can understand the lessons better. They might also use special books and videos to help them learn.
It takes time and practice to get really good at speaking English. But once they do, they'll be able to use English to talk to people all over the world!