An acceleration notice tells you that you must pay off your entire mortgage right away. It says you must also pay all the interest and fees.
When the bank* began to foreclose, they sent you a Right to Cure Notice. The Right to Cure Notice gives you a deadline to catch up on all your missed payments. If you do not catch up by the deadline, the bank can tell you to pay up everything you owe, now. This is “acceleration.”
You may get an acceleration notice. Most mortgages say that once they have “accelerate” your loan, they do not have to let you catch up on missed payments.
But often, if you can pay all your missed payments and any fees, they will accept your payments and stop the foreclosure.
* When we use the word 'bank' we mean your lender. This could be a mortgage company a trust or even a person.