With ellipsis, rather than using a new word, the previously used word, phrase or clause, is left out. The context of what is being said or written makes the meaning clear without the words being there.
I'm going to eat the spicy food but do you think you should eat the spicy food?
They were going to have a big wedding but they've decided not to have a big wedding.
I went shopping in the morning and I went to the doctors in the afternoon.
A: Could you come and see me? B:I could Maybe come and see you.
Are You doing ok?
While you are running you should listen to music.
The man who is wearing the suit is the MP for Greenwich.