A market stall doesn't need a website to look professional — a single QR code, done right, covers most of what a small shop's site would.
The most useful one: payment or ordering
If you take pre-orders or want repeat customers to reach you between market days, a phone QR code or a link to a LINE/Facebook page beats writing your number on a scrap of paper every time someone asks.
A photo of your menu or price list beats a full website
You don't need to build a site. A website QR code pointing to a single photo or a simple page hosted on a free service works fine for showing what you sell and today's prices.
Survive the weather and the crowd
Laminate it — market stalls get rained on, sun-bleached, and handled by dozens of people a day. A plain paper printout lasts about a week outdoors; laminated paper lasts a season. Use dark colors with enough contrast so it still scans after some fading.
Keep it at eye level, not on the table surface
A code lying flat on a table gets glare from overhead lights and shade from your own hand while people scan. Tape it to something upright — a small stand, the edge of your umbrella, a hanging card — at roughly a 15-30° tilt toward customers.