You can find this information out in the head of dpkg -l output, as it's just a formatting convention:
dpkg -l | head -3
Copied here for reference:
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
Description of each field
As you can see from the first three lines:
First letter -> desired package state ("selection state"):
- u ... unknown
- i ... install
- r ... remove/deinstall
- p ... purge (remove including config files)
- h ... hold
Second letter -> current package state:
- n ... not-installed
- i ... installed
- c ... config-files (only the config files are installed)
- U ... unpacked
- F ... half-configured (configuration failed for some reason)
- h ... half-installed (installation failed for some reason)
- W ... triggers-awaited (package is waiting for a trigger from another package)
- t ... triggers-pending (package has been triggered)
Third letter -> error state (you normally shouldn't see a third letter, but a space, instead):
- R ... reinst-required (package broken, reinstallation required)