This sign indicates a road for pedestrians, which cannot be used by cyclists.

In the photo you can see a path along a street, with a round blue sign C-13/16 with a pedestrian symbol above a horizontal line and a bicycle symbol below it. This sign does not mark a path for pedestrians on which cyclists may not ride - the answer is NO.

Sign C-13/16 "path for pedestrians and cyclists" marks a path intended both for pedestrians and for cyclists. So cyclists may use it, and the horizontal line means that pedestrians and bicycles use the same surface. On such a path a cyclist rides carefully and gives way to pedestrians. A footway (droga dla pieszych), only for pedestrians, is marked with sign C-16, and a cycle path, only for bicycles, with C-13. A moped is not among the vehicles for which the Road Traffic Act intends the path for pedestrians and cyclists, so you must not ride onto it on a moped.

Legal basis: § 40 para. 1 and § 39 para. 1 of the Regulation on road signs and signals; Art. 2 point 4b of the Road Traffic Act (Prawo o ruchu drogowym)