As others also say below, the Python/C++ combo is the de facto standard in machine learning and AI today. The second best is R/Rcpp/C++. Other ecosystem has also parallel offers (even PHP has an ML library), but the industry clearly prefers the Python/C++ combo today.
There might be some changes in the future. Rust might get stronger and actually take some share both from C++ (for writing ML libraries) and from Python (for putting ML algorithms in production) in the ML/AI business.
Julia is a strong contender, let us see how far she can go. She has the ambition to dethrone both Python and C++ all at once. But I am personally not sure if it is ever gonna happen.
Other languages such as Go, JavaScript, Kotlin and Swift will also have some roles in using pre-trained algorithms.
But today, the most dominant player is Python/C++ [and it might be perhaps Python/Rust in the future, but this is only my personal fantasy ;)].
