The risk_profile also know as investor profile defines a numerical scale to represent the customer’s willingness and/or capacity to take on financial risk.

As described in this Article from the CFA Institute:

Current regulations reflect the complexity surrounding risk profiling, with many generally vague as to what factors influence a risk profile. Current regulatory guidance also differs among countries

Note the differences in the definitions of investment profiles in Article 25 (2) of MIFID II, and US FINRA Rule 2111.

The scale is based on an internal assessment made by the reporting intitution. It is presented in ascendant order from 1 to 10. However, the reporting instituion does not need to define 10 different risk profiles. This means:

If the reporting instituion has defined 5 different profiles for their investors, a risk_profile of 1 will represent the most conservative investors, while a risk_profile of 5 will represent the most risky ones.