What do the following terms mean for verification engineers?
Basically a specification is a list of requirements. A requirement is generally defined as any statement that has the word "shall" in it.  For example, a specification for a digital multimeter might include the following requirement: " The DMM shall have a display resolution of 3000 counts".
A function is a capability of the equipment. Again, using A DMM as an example, a function would be the ability to measure AC volts.  A feature is a particular capability that makes the device stand out.  For example, the DMM features a wide bandwidth of 100 kHz with the AC volts function, which is better than most DMMs.
Features and functions both must be specified in the requirements or they won't be designed into the device.
Configuration refers to whether the device as designed will meet all of its specifications. Again, for example, if the device uses 5% resistors, it would be hard to verify that is meets an accuracy requirement of 1%.