Wifi extender help

Im a dummy when it comes to anything tech. Our master bedroom gets very weak wifi signal (if any) and I am looking to purchase an extender for better signal.

Couple of questions. What would be my best options? Its only about 50ft from the router/modem but it is on the other side of the kitchen so I assumed there is something with the building materials interfering with the signal.

Also, when I do install the extender, do I connect the device (laptop, ipad etc) do the extenders network or the routers network. Also, do both devices (example security camera, phone) need to be connected to the extender or just the same network.

Thanks in advance!