JavaScript framework is a code library of JavaScript to build web applications or websites. JavaScript frameworks are the pre-written code that allows using routine programming features and tasks. JavaScript frameworks define the entire application design whereas javascript libraries offer functions to be called by its parent code. Angular JS, React JS, Ember.js, Vue.js and Meteor.js are the few examples of the JavaScript framework.
If you are interested to learn the Angular JS framework, I would recommend this Angular course by Intellipaat.
You can watch this video on Angular vs React vs Vue to know about JavaScript frameworks: