lightning-helptext tag with content attribute can be used for Tooltip Text in Salesforce Lightning Web Component.

content attribute in lightning-helptext tag can be used for Tooltip Text in Salesforce Lightning Web Component.

Sample Code:

HTML:

<template>
    <lightning-card>
        <div class="slds-m-around_medium">
            Test<lightning-helptext content="Testing Help Text"></lightning-helptext><lightning-input variant="label-hidden"></lightning-input>
        </div>
    </lightning-card>    
</template>

JavaScript:

import { LightningElement } from 'lwc';

export default class SampleLWC extends LightningElement {}

JS-meta.xml:

<?xml version="1.0" encoding="UTF-8"?>
<LightningComponentBundle xmlns="http://soap.sforce.com/2006/04/metadata">
    <apiVersion>54.0</apiVersion>
    <isExposed>true</isExposed>
    <targets>
        <target>lightning__Tab</target>
    </targets>
</LightningComponentBundle>

Output: