If you see something like A1, B2 or C1, these represent the proficiency of a speaker in a language they're not native in, and are called CEFR levels. They are valid for any language, not only German!
Roughly speaking, A levels are beginners and C levels are experts. Remember that CEFR level are self-assessed and indicative!
You can see more specific names and descriptions on the Wikipedia page:
https://en.wikipedia.org/wiki/Common_European_Framework_of_Reference_for_Languages
🗨 How do I know what level I am?
If the table on Wikipedia is too generic for you, you can try using this one here:
https://rm.coe.int/168045bb52
Just check each column one at a time: if you can do all it describes, move to the next column. Your level is the highest where you can do the most things.
Alternatively, you can use this questionnaire to estimate your level more accurately:
https://rm.coe.int/self-assessment-checklists-from-the-swiss-version-of-the-european-lang/1680492f8e

(45539 uses, 7%, 52.67 uses/day)
(45328 uses, 7%, 70.09 uses/day)
(42570 uses, 7%, 49.23 uses/day)
(37371 uses, 6%, 63.26 uses/day)
(32022 uses, 5%, 37.03 uses/day)
(28968 uses, 4%, 33.5 uses/day)
(23248 uses, 4%, 40.31 uses/day)
(18586 uses, 3%, 21.49 uses/day)
(13880 uses, 2%, 18.63 uses/day)
(8993 uses, 5% 10.4 uses/day)
(7359 uses, 4% 8.51 uses/day)
(6526 uses, 3% 7.55 uses/day)

ich dachte ich schon seit 4-5m hier war