Communications, learning, and writing. This is the house of intellect. It represents what you are vocal about. Many famous writers, singers, artists and media stars were born with Jupiter in the 3rd house: Ernest Hemingway, Johnny Carson, Leonardo Da Vinci, and Cat Stevens to name a few.
What to work on when Jupiter is in your 3rd house: Communications. What you say, think, and write are all magnified. Start a personal blog, write about yourself in your journal, and consider mass-com as a major. What you write may show up in big media, win a Pulitzer prize, or get sold to be a Netflix original series.