What does each of these codes do? [on hold]

I am new to web design and development in PHP. I know how some code works and other codes I have no idea about. I was just wondering if anyone could explain to me in a general or board term, what each of the below codes do so I can get an understanding of them. A simple and clear explanation is fine I am not looking for detailed definitions or examples. Thank you.

$result = mysqli_query($connection,$query);

$num_rows = mysqli_num_rows($result);

$row[]=mysqli_fetch_array($result);

(mysqli_query($connection,$query)

$row_count = mysqli_num_rows($result);
if($row_count > 0){

$count=mysqli_num_rows($result);