What is uvm analysis port?

Analysis port (uvm_tlm_analysis_port) — a specific type of transaction-level port that can be connected to zero, one, or many analysis exports and through which a component may call the method write implemented in another component, specifically a subscriber.

port, export, and imp classes used for transaction analysis.

uvm_analysis_port :
Broadcasts a value to all subscribers implementing a uvm_analysis_imp.
uvm_analysis_imp :
Receives all transactions broadcasted by a uvm_analysis_port.
uvm_analysis_export : 
Exports a lower-level uvm_analysis_imp to its parent.