Apologies to anyone reading that my understanding of this memorial is limited, but I think it represents where 150 Poles died on 1 August 1944 as part of the Warsaw Uprising, in this case fighting against the German Luftwaffe. The panel on the left notes that this is a place sanctified with the blood of Poles who died for the freedom of their homeland, with the panel on the right referring to the Home Army Regiment known as Baszta, fighting near to Fort Mokotów. This memorial was placed here in 1997, replacing a previous temporary plaque.
There’s more information at http://www.sppw1944.org/index.html?/mapapowstania3/m_34.html.
I posted this as every time I visit Warsaw I am reminded of the great bravery of the Polish troops and residents who defended themselves with such courage against a German onslaught.