What does this even mean?

42x=7

It means that something times 42 equals 7. If you have to find the value of x then you would have x=0.16666 repeating or 1/6

Divide 42 on both sides

42x/42 will cancel out leaving x

x=7/42

x=0.16666 or 1/6

It means that you need to divide 42 on both sides

42x/42=7/42

0.166 ...