First, the young knight must train under a squire as a page.
Teach me to be a squire!
Sure, but it will take 7 years of training.
The page then spends the rest of his time in the castle helping the ladies of the castle. Pages also learned how to ride a horse, got religous instruction, and learned skills from the lady like singing and dancing.
After 7 years, the page becomes a squire, who serves a knight that is their lord. They perform services like serving the knight food, taking care of their equipment, and taking care of their horse.
Here is your horse, my lord.
Most importantly, squires trained with swords, lances, spears, battleaxes, and maces. Squires also tended to their lords in real battles.
If they were deserving, a squire in their early twentys, after undergoing a complex religous, was knighted by a lord using a sword.