<YTLink YtId="4_wrJAXEMng" YtTime={42} />

YTLink.jsx

// This is needed for any .jsx file
// JSX allows you to use HTML tags in JavaScript
import React from 'react'

// Give a **number**, return mm:ss
function formattedYtTime(sec) {
  // minute
  const h = Math.floor(sec / 60)
  // second
  const s = sec - h * 60
  // pad second to 2 digits
  const ss = String(s).padStart(2, '0')
  return h + ':' + ss
}

// A normal way to do it.
function YTLink(props) {
  // Pick the items
  const YtId = props.YtId
  const YtTime = Number(props.YtTime)
  const url = `https://youtube.com/watch?v=${YtId}&t=${YtTime}s`
  const text = formattedYtTime(YtTime)
  // Unlike Vue, in React you do NOT use :key=val but key={val}
  return (
    <a href={url} target="_blank" rel="noopener noreferer">
      <i className="fa-solid fa-stopwatch" /> {text}
    </a>
  )
}

// ... or you can write "url" and "text" directly in the code.
function YTLink_2(props) {
  const YtId = props.YtId
  const YtTime = Number(props.YtTime)
  return (
    <a
      href={`https://youtube.com/watch?v=${YtId}&t=${YtTime}s`}
      target="_blank"
      rel="noopener noreferer"
    >
      <i className="fa-solid fa-stopwatch" /> {formattedYtTime(YtTime)}
    </a>
  )
}

// ... or you can pick the variable you want directly.
// https://es6.ruanyifeng.com/#docs/destructuring#%E5%AF%B9%E8%B1%A1%E7%9A%84%E8%A7%A3%E6%9E%84%E8%B5%8B%E5%80%BC
function YTLink_3({ YtId, YtTime }) {
  return (
    <a
      href={`https://youtube.com/watch?v=${YtId}&t=${YtTime}s`}
      target="_blank"
      rel="noopener noreferer"
    >
      <i className="fa-solid fa-stopwatch" /> {formattedYtTime(Number(YtTime))}
    </a>
  )
}

// ... or you can use the arrow expression.
// Note it's "const YTLink_4", not "function YTLink_4"
// https://es6.ruanyifeng.com/#docs/function#%E7%AE%AD%E5%A4%B4%E5%87%BD%E6%95%B0
const YTLink_4 = ({ YtId, YtTime }) => (
  <a
    href={`https://youtube.com/watch?v=${YtId}&t=${YtTime}s`}
    target="_blank"
    rel="noopener noreferer"
  >
    <i className="fa-solid fa-stopwatch" /> {formattedYtTime(Number(YtTime))}
  </a>
)

// Don't forget to export the function you need :D
export default YTLink