'Should' shows what is right or wrong to do. It expresses moral duty or responsibility.
You should respect your parents.
People should help each other.
'Should' shows that we think something will happen or is true. It tells about what we expect to be real.
The train should arrive soon.
She should be at home now.
'Should' can be used to ask politely if you can do something or offer help in a nice way.
Should I help you with that?
Should we call a doctor?
'Should' is used in indirect speech to report what someone said or thought would happen.
She said she should come later.
He thought we should wait here.
Here, 'should' shows something is expected but not done well. It can show criticism or surprise.
You should tell the truth more often.
He should be more careful.
