how does your brain function??

Brains are a collection of nerve cells. Nerve cells evolved quite early in the history of multicellular animals. they are a way to send, receive and process information. For example, the muscles will contract when a nerve sends signals to it to contract. People who are bitten by cobras have their muscles paralyzed by cobra venom, since the venom flood the nerve cells with chemicals that block the sending of signals. When the muscles that control breathing no longer receive any nerve signals, they stop and a person dies as a result.

The brain contains a lot of nerve cells, and these nerve cells are connected to one another. They receiver signals from nerve cells located around the body, which may sense things such as light, heat, and touch. When these signals are sent to the brain via nerve cells, the brain processes the information and sends out signals to instruct the muscles as to what they should do. A signal to the brain that the body is cold may prompt the brain to send out signals for the muscles to shiver, so that these shivering muscles will generate heat and raise the body temperature. If the eyes send signals to the brain that there is a dangerous animal ahead, then the brain will process the signal and send signals to the body to either freeze, fight or escape.

Primitive animals may have simple brains, and these brains do not process information the same way our brains do. We have a forebrain that can be used to think and also to override our instincts. For example, when we are angry, our instinct may be to fight the person who makes us angry. However, sometimes but not always, our forebrains will evaluate the consequence of fighting (e.g. the possibility of getting hurt and/or the possibility of being arrested and charged with crimes) and may be able to stop ourselves from engaging in a fight instead.

Good question. no good answer.

A miracle from God. Functions of our body system is too.

atheists have an even harder time explaining it

"How does your brain function?? (sic)"

I recommend a textbook on neuroscience.

Your brain in constantly sending signals all over your body telling it what to do

Study evolutionary theory related to humans