'=' expected?

I would like to ask what '=' expected means. It say's on that on line 5 I need and = but I don't know where! Here is my code:

while true do
    turtle.attack(4)
    if turtle.getItemCount(16) then
    turtle.dropDown
    repeat
end 

Split into new topic.

You're missing the parentheses on line 4, so it thinks you want to change the value of turtle.dropDown instead of calling it. Add parentheses to that line (making it `turtle.dropDown()`), remove the repeat on the next line, and add another end at the end of the program.