Organic traffic is visitors who arrive from unpaid search results, as opposed to ads, social posts, email or links on other sites.
It grows slowly at first, as pages get indexed and start ranking, but it keeps arriving without new effort for each visit.
In Google Search Console it shows up as clicks; impressions are how often your pages appeared in results at all.
Why it matters for a launch
Launch traffic is a spike; organic traffic is the steady stream that keeps a small product growing after launch day.
Read more: Why a new website isn't on Google