Those red circles on your picture, what you want in those locations are called a switch or switching hub.
Do NOT get a plain 'hub' aka repeater (although they are very out of date so probably you wouldn't find one anyway)
Also, check the backplane capacity. It should add up to the number of ports x full duplex throughput per port - if it's significantly less then it's a cheap switch. It will work, but it means you can't run all ports at maximum throughput at the same time, so if all your computers are transferring large files you will get slowdowns.