To change something slightly to make it better or more suitable.
Adjusting something is usually a good thing. It can make things work better or fit better.
Examples:
I need to adjust my chair so I can reach the table.
She adjusted the radio to make the music louder.
He adjusted the picture on the wall so it was straight.
I had to adjust my hat because it was too big.
The robot adjusted its arms to pick up the small toy.
We had to adjust the plan because it was too hard.