The class was one of students who had come to the UK from around the world to improve their English. The teacher was asking them why on earth they would want to learn English. The theory of his lesson was in the right place, pointing out the importance of all sorts of other languages on the planet. The person from Spain clearly already knew Spanish, a widely-spoken international language. Perhaps the person from Korea, wanting to go into business, would be better-off learning Chinese.
A young man said he wanted to study physics in the UK, which is why he was here to improve his English. The teacher responded, "Physics? Wouldn't you be better off studying Greek and Latin?"
Relatedly, did you know that English is such a common language worldwide because of boats? Britain is a small island, and so had lots of boats for trading, and English spread wherever those boats went.*
* Sort of like the plague then. I wonder what the transmission mechanism was? Also, please note that by implication, colonialism had nothing to do with the process.