What is Lightning Component Bundle in salesforce lightning?

Lightning Bundle contains Component,Controller,Helper,style,documentation,rerender,design,SVG with it.

Application

While creating a lightning application is created automatically with a standard application. The lightning application stores only HTML tags.
The only required resource in a bundle. Contains markup for the component or app. Each lightning bundle contains only one component or app resource.

ForceLearn.app

<aura:application>
    <h1> Myfirst application </h1>
</aura:application>

Component
Lightning components are mostly used HTML tags and we can use markup and HTML5 are also supported.

ForceLearn.cmp

   <aura:component >
     <h1> my First component </h1>
 </aura:component>

Controller

It Contains client-side controller methods to handle events in the component. It supports javascript to run functions in components actions and each function has three parameters like component, event, and helper.

ForceLearnController.js

( 
   { 
      myAction : function(component, event, helper) { 
      } 
    } 
)

Helper

JavaScript functions that can be called from any JavaScript code in a components bundle.

ForceLearnHelper.js

   ( 
      { 
       helperMethod : function(){ 
       } 
      } 
   )

CSS

Contains styles for the component. we can customize the application with CSS with custom CSS.

ForceLearn.css

.THIS{
  }

Documentation

In Documentation, we can design the description, sample code, and one or multiple references to example components.

ForceLearn.auradoc

   <aura:documentation>
     <aura:description>Documentation</aura:description>
     <aura:example name="ExampleName" ref="exampleComponentName" label="Label">
     Example Description
     </aura:example>
 </aura:documentation>

Render

Client-side renderer to override default rendering for a component.

ForceLearnRender.Js

( 
       { // Your renderer method overrides go here
   } 
)

SVG

By using SVG, we can Custom icon resources for components used in the Lightning App Builder or Community Builder.

ForceLearn.SVG

    <?xml version="1.0" encoding="UTF-8" standalone="no"?>
    <svg width="120px" height="120px" viewBox="0 0 120 120" version="1.1"
    xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
    <g stroke="none" stroke-width="1" fill="none" fill-rule="evenodd">
    <path d="M120,108 C120,114.6 114.6,120 108,120 L12,120 C5.4,120
    0,114.6 0,108 L0,12 C0,5.4 5.4,0 12,0 L108,0 C114.6,0 120,5.4 120,12 L120,108 L120,108 Z"
    id="Shape" fill="#2A739E"/>
    <path d="M77.7383308,20 L61.1640113,20 L44.7300055,63.2000173
    L56.0543288,63.2000173 L40,99.623291 L72.7458388,54.5871812 L60.907727,54.5871812
    L77.7383308,20 Z" id="Path-1" fill="#FFFFFF"/>
    </g>
</svg>

All combination of above contains Lightning Bundle in salesforce lightning

Learn more about the basics of lightning component