I found that learning and writing some Clojure and Go made me think better about the code I was writing in my main language (python).
I enjoyed working through Clojure for the brave and true: https://www.braveclojure.com/clojure-for-the-brave-and-true/
and the go tour is probably the best introduction I've ever had to a language: https://tour.golang.org/welcome/1