Signs like these seem to be specific to Jurmala and have no meaning from the perspective of Traffic Law. Community discussions can be seen in Zulip chat (requires registration):
https://osmlatvija.zulipchat.com/#narrow/stream/360539-veloinfrastrukt.C5.ABra/topic/J.C5.ABrmalas.20pa.C5.A1izdom.C4.81tas.20z.C4.ABmes
...or in public Zulip archive (does not require registration):
https://osmlatvija.github.io/zulip-archive/stream/360539-veloinfrastrukt.C5.ABra/topic/J.C5.ABrmalas.20pa.C5.A1izdom.C4.81tas.20z.C4.ABmes.html

This is a two-way street (both for bicycles and for motor vehicles).