The modal verb ‘can’ is used for :

1. Talking about abilities
2. Asking for permission
3. Making requests

For ability
I can clean tables.
I can take orders.
I can start next Monday.
I can speak two languages.

For permission
Can I have a job ?
Can I start next week ?
Can I help in the coffee shop ?
Can I go to the party ?

For requests
Can you start tomorrow ?
Can you write a cover letter ?
Can you help me ?

CAREFUL!
To change to the negative :
Can + not or ‘nt

EXAMPLE
I can’t start tomorrow.
I can’t take orders.