Sorry to hear about your dad.
They can sell the house without you but as a child, you could always make a claim on that house once the terms of the sale have been agreed to (called a caveat) - or even after it’s sold.
The something is very likely getting you to state that you don’t have a claim (or give up your claim) on the title.
Get a lawyer, as this could be very different to how things work in your part of the word, to go through it with you (though without a lawyer, you could potentially argue you were coerced into signing during a tough time in your life).