What does the number on the card mean

Just the number after the golden icon of lingq at the far left of the word card, I really want to know, thank you

That significance word importance. A word can be worth 1-4 coins. Most common word in a language (most important words) are worth 4 coins and so on. You will earn more coins for saving those words or making them known.

Thank you so much!
I’ve been stuck with this