<= has the expression evaluate to true for 'less than or equal to'.
e is Entitye.expected_aum <= 10000000
Let's say that e, the entity in the case where this expression is used, is a small financial advisory firm in Lyon. The expression evaluates to 'true' if the firm, after a difficult year, is expected to have ten million or less in assets under management.
This could mean it no longer qualifies for certain services your organization offers to its bigger corporate clients with ten million or more in assets under management.
By attaching this condition to those documents that are more relevant to medium size enterprises than to large ones, you make sure you offer services, and collect information, relevant to a firm with ten million or less in assets under management.