how can i get free traffic

Improve your SEO.
List your business on Google My Business.
Optimize your website's performance.
Link building.
Promote your website on social media.

You will not clarify what kind of free traffic you are looking for. Usually, it is social media and SEO, but both are pretty hard to say that it is free. Because all is effort and your time or the time of some people, that also costs some money.

Like others have said. Create a presence on social media. Make videos relevant to your niche, and upload them to youtube. Include your website somewhere in the intro.