Look at this sentence:
The water was dripping through the kitchen sealing.
The word 'sealing' is correctly spelt, but it is the wrong word for this sentence. The correct word is actually 'ceiling'. The two words are homophones, which means that they are pronounced the same way but mean different things.
This worksheet contains sentences where the writer has chosen the wrong homophone. You need to correct the homophone each time, so you may find a dictionary helpful.