This response is really pedantic, but I'm sure that it may be helpful to anybody who is new to wet shaving......
I think what they're saying is that some people will do 100% of the lathering, right on their soap, before the brush ever touches their face, and when they go to their face, the brush is covered in a quantity of fully formed lather and they're simply using the brush to spread the lather around.
This is what I used to do with hard soaps and a boar brush.
Some people have a cake of soap in one bowl, and only keep the brush on it long enough to get the brush soapy, but not develop any lather. Then they use a moss scuttle or a different bowl to build the lather before using the brush as a mop to spread it on their face.
And, of course, other people will load the brush with unlathered soap or creme, and to all the lathering right on their face.