In the visible situation, when transmitting this light signal do you have the right to turn left at the intersection?

In the photo you are approaching a junction with traffic lights along a wide street in a city; the traffic lights on the left show green, above them there is sign B-21 "no left turn", and sign C-9 stands on the traffic island. While the green signal is showing, you are not allowed to turn left - the sign prohibits it, and the light does not cancel the sign. The answer is: no.

The Regulation on road signs and signals states that sign B-21 "no left turn" prohibits turning in the direction shown on the sign and making a U-turn, and the prohibition applies at the nearest junction; a green signal on traffic lights S-1 only means permission to drive past the traffic lights. The Road Traffic Act states that light signals take precedence over signs regulating right of way - B-21 is not such a sign, so it applies whatever the colour of the light. Green tells you when you may go, and the signs tell you which way. A left turn is not provided for in the traffic light programme here, so even on green you would cross the path of oncoming vehicles, which do not expect such a manoeuvre. You go straight on or turn right and look for another route to a destination on the left.

Legal basis: § 22 para. 1 and 2 and § 95 para. 1 point 1 of the Regulation on road signs and signals; Art. 5 para. 3 of the Road Traffic Act (Prawo o ruchu drogowym)