What do three dots "./..." mean in Go command line invocations?

From the command go help packages:

An import path is a pattern if it includes one or more "..." wildcards, each of which can match any string, including the empty string and strings containing slashes. Such a pattern expands to all package directories found in the GOPATH trees with names matching the patterns. As a special case, x/... matches x as well as x's subdirectories. For example, net/... expands to net and packages in its subdirectories.

go [command] ./...

Here ./ tells to start from the current folder, ... tells to go down recursively.

For Example:

go list ...

In any folder lists all the packages, including packages of the standard library first followed by external libraries in your go workspace.