A feeder feeds the ball over the net for an attacker to move in. Make an attack approach and hit, while the blocker looks at how the attacker lines up on their approach and jumps and blocks.
Be aware, the feed has to be accurate as you don't want the attacker jumping into the net and injuring the blocker. If you do a bad feed make the hitter realise they should not jump.
New hitters rarely miss because of their arm. They miss because of their feet. Build a reliable approach, then time it with your setter.
When your hitter gets stuffed, five teammates standing and watching is how you lose the point. Good attack coverage turns a blocked ball into a second swing.
Coaches spend hours correcting arms in serve receive when the real fault is almost always the feet. Fix the movement and the platform fixes itself.