Client to Client

How do i send information from one client to an other client, if i say have 10 clients connected.
Client 2 wants to say “Hello World” to client 4.
(in blueprint)

You are talking about a chat system. Luckily there is one available in the marketplace.

Simple Multiplayer Chat System

This works very well and I have bought it myself to learn how the chat system works. Unfortunately it is difficult to cover a working solution for you and I suggest you buy this pack to see how it was done.