Whenever you see the magnifying glass icon within SAP it means there is a 'formatted search' assigned to that field.

NB. A formatted search enables SAP Business One to enter values, originated by a predefined
search process using SQL (a type of computer programming language) to a specified field in the system.
The following are examples of how formatted search function can be used:
  • Automatic entering of values into fields based on various objects in the system
  • Entering values into fields using a pre-defined list
  • Automatic entering of values into fields via pre-defined queries (defined by the administrator)
  • Creating dependence between fields in the system. For example, the value in field X influences the value in field Y
  • Displaying fields that can only be displayed using queries. For example, User Signature,Creation Date, Open Checks Balance (for business partner), etc.