Are merging into traffic behind this information signs?

In the photo you are driving out of a housing estate street onto a road; on the right there are signs D-41 "end of residential area" and D-47 "end of internal road", and further on sign C-2, which requires a right turn. When you drive out beyond these signs, you are joining traffic (włączanie się do ruchu). The answer is: yes.

The Road Traffic Act states that joining traffic takes place, among other cases, when entering a road from a road that is not a public road and from a residential area, and a driver joining traffic must exercise particular caution and give way to other vehicles and road users. The Regulation on road signs and signals states that sign D-41 marks the exit from a residential area, and D-47 - the exit from an internal road onto a public road. The place where you are driving out is not a junction, so the right-hand rule does not apply here - you give way to everyone: vehicles from both sides, cyclists and pedestrians on the pavement that you are driving across. You stop before the roadway, check both sides and move off to the right when the road is clear.

Legal basis: Art. 17 para. 1 point 1 and para. 2 of the Road Traffic Act (Prawo o ruchu drogowym); § 58 para. 1 and 5 of the Regulation on road signs and signals