What does flex mean here?

Question

css

Actually the title. In a lesson on another topic, I saw such an application of flex ( https://imgur.com/a/q9SRj0o ) and did not understand. It has other meanings, wrap there, column, and a bunch more. What do these numbers mean here? Explain. What did I miss

Answer 1

this is a short entry,
three properties are combined here
flex-grow: 0
flex-shrink: 1
flex-basis: 33.33%