Use:

Getters and setters in LWC are used to:

Control how a property’s value is accessed or modified.
Implement computed properties based on other properties.
Validate or transform data before setting a property.
Trigger side effects when a property is read or updated.

userComponent.html

<template>
    <lightning-card title="User Information">
        <lightning-input label="First Name" value={firstName} onchange={handleFirstNameChange}></lightning-input>
        <lightning-input label="Last Name" value={lastName} onchange={handleLastNameChange}></lightning-input>
        <p>Full Name: {fullName}</p>
    </lightning-card>
</template>

userComponent.js

import { LightningElement, track } from 'lwc';

export default class UserComponent extends LightningElement {
    @track firstName = '';
    @track lastName = '';

    get fullName() {
        return `${this.firstName} ${this.lastName}`;
    }

    handleFirstNameChange(event) {
        this.firstName = event.target.value;
    }

    handleLastNameChange(event) {
        this.lastName = event.target.value;
    }
}

Getters and setters in LWC provide a powerful way to manage component state and implement custom logic for property access and modification. By leveraging getters, you can create computed properties that automatically update based on other property values. Setters allow you to define custom behavior when setting property values, enabling validation, transformation, and other side effects. Understanding and utilizing getters and setters effectively can help you create more dynamic, maintainable, and responsive Lightning Web Components.
Happy Coding!