SoapUI Properties can be defined in the gui and then referenced using a Property Expansion in later parts of the test.
These expressions can be inserted into payloads, Groovy code or entered as values for downstream Properties.
Some examples -
${#Project#PropertyName} – For Project Level
${#TestSuite#PropertyName} – For Test Suite level
${#TestCase#PropertyName} – For Test Case level
${TestStepName#PropertyName} – For Test Step level
${#MockService#PropertyName} – For MockService property
${#Global#PropertyName} – For Global properties, found in File → Preference → Global properties tab. This property can be used across all projects
${#System#PropertyName} – For System Property, found in Help → System properties
${#Env#PropertyName} – For environment variable