Yes, Python 3 allows Greek letters in many variable names. Its keywords, such as if, for and return, still use Python’s defined spelling. A programmer’s nationality does not tell you which naming conventions they use.
A working example
α = 2
β = 3
print(α + β)
print("Καλημέρα")The output is 5 followed by Καλημέρα. Save the source as UTF-8. You can use Greek text in strings and comments without using it in identifiers.
Identifier rules still apply
A name cannot begin with a digit, contain spaces or reuse a reserved keyword. Not every Unicode symbol is a valid identifier. You can check a candidate with str.isidentifier(), and use keyword.iskeyword() separately to check reserved keywords.
import keyword
print("α".isidentifier())
print("2α".isidentifier())
print(keyword.iskeyword("for"))This prints True, False and True. Choose names your collaborators can read and type, and avoid mixing visually similar characters from different alphabets.
For punctuation inside text, see apostrophes in Python strings. For a complete beginner example using named values, try a student grades dictionary.
Sources and verification
Both Unicode examples are executed in the local Python verification run. This article makes no claim about the habits of Greek programmers.