Although the US is officially divided into 9 time zones, the quantity of the time zone IDs is much bigger. America/Puerto Rico is one of them. This identifier shows what time is it in exact location now. In this case it is about the time in the US territory.
America/Puerto Rico time now
You can see the current time and date of America/Puerto Rico time zone here:
Current time in Puerto Rico, PR?
Since the time in Puerto Rico is taken as the basis for the identifier America/Puerto Rico, the current time in this area is the same:
Standard time of America/Puerto Rico
STD of America/Puerto Rico is UTC -4:00 (AST)
Standard time is the local time in America/Puerto Rico time zone when DST (Daylight Saving Time) is not in use.
Daylight Saving Time of America/Puerto_Rico
DST of America/Puerto Rico is UTC -4:00 (ADT)
It means that Daylight Saving Time is not observed in this location.
Daylight Saving Time is not used in any US territories, but it is actively observed in most states, as well as outside the USA.
Read more about “Abbreviations for Time Zones, names and locations” which are used for identification of Coordinated Universal Time, like EDT, CEST EST, AKDT and others.
America/Puerto Rico time zone
America/Puerto_Rico is the ID which refers to Atlantic Time Zone. Its borders and the states which included to this time zone can be seen on the map of US time zones.