"When is your internship?"
Translation:מתי ההתמחות שלךָ?
I don't think it's common in native speakers, but adult learners can be confused when encountering a new word. It may be helpful to remember that הת...ות is a pattern of many nouns, it often implies "becoming something" (but not always). There are several patterns that start with an ה, it is one of those letters (also ת, מ) in addition to its being the definite article.