Assume that Staphylococcus aureus grows on nutrient agar with up to and including 15% (w/v) NaCl, while Escherichia coli cannot grow on nutrient agar with more than 10% (w/v) NaCl. What does this mean

This means that Staphylococcus aureus is more tolerant to salt (NaCl), however, E. coli is sensitive to NaCl concentrations more than 10%. This also means that Staphylococcus has more fluid in its cytoplasm, as compared to E. coli, which enables it to tolerate in high salt concentration. Further, this also indicates the ability of both microbes to grow on different media compositions and have different nutritional requirements.