Sandstone - Basement spots on the floor

What are these stains on the floor, additionally there is black mold on an interior wall in the basement. Additionally, there are salt crystals on the wall like small hairs. Also the stains on the wall, the brown ones,

Salt efflorescence and mold are signs of moisture in the masonry/concrete floor and should be repaired in the medium term. Causes should of course also be addressed, such as [drückendes Wasser von außen].