The first line is obviously the language version. What is the second line in IDLE at startup? It looks like the ID of a C-compiler.
Here it is for version 2.7 (GCC):
Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 26 2016, 12:10:39)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
... and version 3.7 (Clang):
Python 3.7.3 (v3.7.3:ef4ec6ed12, Mar 25 2019, 16:52:21)
[Clang 6.0 (clang-600.0.57)] on darwin
More importantly what does it mean for the language? Is it the Python interpreter's compiler and does it mean something about speed and performance of this version of the language? I always think of this language in terms of being "interpreted" and not "compiled" so how does knowledge of the interpreter's compiler benefit me as a programmer?