When you click Fields nodes the list of all fields contained in the table is displayed in the right panel.
Clicking on a particular field shows specific information about this field.
In "Source field info" group you can see initial field information, as it was in source database: Name and Field type.
"New field info" shows options to configure the same field in the target database. For example you can rename the field or change its data type.
Choose the needed data type from drop-down list "New type" .
NOTE: In order to avoid data loss "Include only safe types" option is checked by default. It restricts data types list to compatible types only for the target database. If checked only similar (relational) types to the source type will be displayed in the "New type" edit box.