Google sandbox is a probation period set by Google to observe new websites for a while before sending any significant amount of organic traffic.
During this period most new websites receive near to none organic traffic. Google analyzes the new websites with test traffic that are driven from the random search terms that are usually not the targeted keywords on pages.
Does it really exist?
When it comes to the existence of Google Sandbox there are opposing opinions.
One part of the SEO community is certainly sure it exists, while the other part thinks it is just another SEO myth.
Here is John Mueller's response to a question asked him about the topic.
"With regards to sandbox, we don’t really have this traditional sandbox that a lot of SEOs used to be talking about in the years past.
We have a number of algorithms that might look similar, but these are essentially just algorithms trying to understand how the website fits in with the rest of the websites trying to rank for those queries. […]
It’s always kind of tricky in the beginning when we have a new website and we don’t quite know where we should put it."
Although the existence of this time period has never been acknowledged by Google, the idea of its presence is well respected in the SEO community. Because there's a lot of convincing evidence to think so. If you want to learn more about Google Sandbox you can visit more in depth information at https://metriculum.com/google-sandbox/
