Well, if you have turn indicators it'd be better if you used them. But if that's all you've got it's usually OK.
Added: YES, that is the correct hand signal.
Yes.
Hand signal: put your arm straight out of your left hand window and fix the light before a cop sees it
To indicate stopping or coming to a halt while driving, use the hand signal of extending your left arm out of the window and pointing downward. To signal a left turn, extend your left arm straight out to the side. To signal a right turn, extend your left arm out of the window and point upward.
just turn your arm left but not all the way you might break it. It depends which country you are in and what side of the road. In the USA, it's simple, arm straight out of the drivers window. In the UK, where you are sat on the right side of the car. With your arm out the window, make a circular anti-clockwise motion using the whole arm. As if it's an invitation to those following, to pass down your righthand side, as you are going to turn.
If your turn signals break, you can use hand signals to indicate your intentions while driving. To signal a left turn, extend your left arm straight out the window. To signal a right turn, extend your left arm out the window and bend it upward at a 90-degree angle.
stick your left arm out of the window
Left arm out the window, bending 90 degrees straight up at the elbow, all fingers together pointing straight up.
stick your left arm out of the window
Hold the arm straight out.
straight left arm out of the driver seat
. . . be making a left turn.
To indicate a left turn while cycling on the road, extend your left arm straight out to the side. This hand signal communicates to drivers and other cyclists that you intend to turn left.