Hi! Primary sources are also called original sources, such as an old document or a ancient weapon. For example, if a historian is trying to find out more about the Gold Rush and digs up an old pickaxe, the pickaxe is a primary source to finding out more about the Gold Rush.
Secondary sources are like your history textbook. Historians also use books and data already collected to support their findings. Using the example I just used, if a historian uses a book about the Gold Rush to support the theories made based on the pickaxe, he or she is using a secondary source!
Hope this helped!