display flex in css means

1.container {
2     display: flex;
3     align-items: center;
4     justify-content: center;
5}
6
7//My youtube:'https://www.youtube.com/HasibulIslambd' 

1.container {
2  flex-direction: row | row-reverse | column | column-reverse;
3}

1.item {
2  flex-shrink: 3; /* default 1 */
3}