With (html) you can do a lot of things for example settingt the base for You're website

With (Css) you can style all you're Html code

with JS/javascript you can create a funktion with you're website

With (C++) you can mostly do everything for example creating games and more

With (JAVA) you can make a lot of android stuff java is mostly used for programing stuff or websites for phones

(Flexbox) Is not a singel property it's a like a key for (Css) Flexbox is used for making you're text flex no mather how long the text is and more

(C++) is used in developing many enterprise software as well as advanced applications like flight simulation and radar processing

(Grid) is like a blueprint for making websites it's mostly used for keeping elements aligned

With (swift) you can do server side scripting