A boolean variable holds one of two values: true or false. Nothing else.
boolean isLoggedIn = true;
boolean hasPermission = false;
You'll use booleans constantly in conditions. Every if statement, every while loop, and every comparison produces a boolean. When you write age >= 18, the result is a boolean that's either true or false.
Name your boolean variables as yes/no questions. isReady, hasItems, canDelete. This makes your code read like English: if (isReady) reads as "if is ready." Compare that to a vague name like flag or status, which tells you nothing about what's being checked.