Thank you Bob

My context:
"Scollon & Scollon's concept of "distribution of talk" which refers t the mutual agreement between individuals as to who talks first, *holds the floor*, how each takes a turn or interrupts is useful here..."

I'm not sure about the meaning of "holds the floor".
Is it who has the right to speak, or who dominates the conversation and speaks most of the time?

Thank you very much

The humble frog guess:
"holds the floor" = "takes control"
Experts will certainly add on...

No experts here. But I can tell you that holding the floor/yielding the floor has to do with parliamentary procedure regarding who will speak.

"Floor" as in (Merriam-Webster) 5c:

5b : the members of an assembly. Took questions from the floor. c : the right to address an assembly. The senator from Utah has the floor.

Thanks Michael and ESC. in this case it's a communication between people.
I understand that it is the one who has the permission to talk.

Almost. "Permission" sounds like a mutual agreement, but "holding the floor" can be imposing one's will by not allowing another to speak. A bit of bullying. (Not always rude, but often forceful. Sometimes with permission.)