There are many possibilities for volunteering work or internships in Colombia. Especially, teaching English to kids and/or guides is one of the main possibilities to get involved! For example, in remote areas like Caño Cristales, Hato Aurora or the Pacific Coast! In Cali it is even possible to teach English in salsa schools and receive salsa classes in return. Most of the time, homestays are included which is the perfect way for you to dive into the Colombian culture and improve your Spanish knowledge.
Concerning an internship in Colombia (also possible in Ecuador, Peru and Bolivia), it would be best to spend at least 5 to 6 months in this beautiful country. Here you can get to know the daily work of a tour operator and especially support with your language skills. If you would like to be off the beaten track, it is also possible to do an internship in the Amazon jungle and help out with daily activities and get to know the tasks as a tour guide.
Just drop me a line, if you are interested in being part of developing a great future for tourism in Colombia!