Are you warned in this situation of a junction with the road on the right?

The sign in the photo is A-12b "road narrows on the right": on the symbol, the right edge moves towards the centre line, and the left edge runs straight. It warns that the roadway narrows on the right side, not of a road joining from the right. The answer is: no.

A minor road joining from the right would be indicated by sign A-6b, and a one-way entry by A-6d - both have a junction symbol, not a narrowing. The Regulation on road signs and signals says that the A-12 signs warn of the roadway narrowing on the side shown on the sign, which may obstruct traffic. In the photo, the right lane ends at a barrier, so drivers on the right will have to move to the left - leave room for them and drive at a steady speed.

Legal basis: § 7 para. 3 point 2 and § 5 para. 2 and 4 of the Regulation on road signs and signals