helloworld.html

<!--Component Start-->
<template>
    <lightning-card title="Hello World" icon-name="custom:custom14">
        <div class="slds-m-around_medium">
            <p>Hello, {greeting}!</p>
            <lightning-input label="Name" value={greeting} onchange={namechangeHandler}></lightning-input>
        </div>
    </lightning-card>
</template>
<!--Component End-->

helloworld.js

//The import statement imports LightningElement from the lwc module
import {LightningElement, track} from 'lwc';
//The export default keywords export a HelloWorld class for other components to use.

export default class HelloWorld extends LightningElement {
    //To execute logic each time a public property is set, write a custom getter and setter with @api.
    //To hold the property value inside the getter and setter, use a private property @track.
    @track greeting = 'World';
    //Input on change method
    namechangeHandler(event) {
        this.greeting = event.target.value;
    }
}

helloworld.js-meta.xml

<?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata" fqn="helloWorld">
    <apiVersion>45.0</apiVersion>
    <!--To allow the component to be used in Lightning App Builder or Community Builder, set  isExposed to true-->
    <isExposed>true</isExposed>
    <!--Targets to make component available for lightning app page, record page and home page-->
    <targets>
        <target>lightning__AppPage</target>
        <target>lightning__RecordPage</target>
        <target>lightning__HomePage</target>
    </targets>
</LightningComponentBundle>

Output: