This is a tomato plant (Solanum lycopersicum). This is a very good plant because:
A classic vegetable, essential to many cuisines. Very easy to grow from seed, and if you are a real pro, you can attempt grafting it too! A very hard-to-kill plant that you can train and prune however you want. It will leave a smelly, greenish brown residue on your fingers so wear gloves.
You can learn more about this plant here.