Are words in the lessons everyday Hindi usage?

One of my Hindi friends (real Indians, real Hindi native speaker from Mumbai and some other northern parts of India where Hindi are spoken) told me that "some" words are not common, and if I use them, no one will understood what I'm trying to say. For example, "यातायात बत्ती". He told me that nobody uses that word (hardly knows what it means). He said, if I say "traffic lights" everybody will get it. Just wonder if that's true?

hi Charoenvit Yes, to some extent there is a great inclusion of English words in the new generation's language. To be absolutely and blandly honest, one could go around India with a good knowledge of English and a bits and pieces of the local language/Hindi. The purpose of this course is to make the learner familiar with Hindi even if there are some terms which are obsolete in today's times. hope you have fun learning hindi.

धन्यवाद. Thank you for your answer. And yes, I enjoy learning Hindi a lot, even though it's a bit कठिन है.