Looks like you’re baking a lot today, rebyidd! A heaping tablespoon is a tablespoon without the top leveled out. You don’t have to use cups- use a regular-sized spoon if you don’t have a teaspoon measure. (A regular sized spoon is the size of a tablespoon and a smaller spoon is the size of a teaspoon, if I’m not mistaken.) In cups it would probably be about one cup.
Btw- Siri is very good at answering these questions (not that I C”V have an iPhone 😉 )