Why has a cell the value because the cell is empty when we see the cell?

Sometimes, a cell is empty when we see it, but the cell is indicated as an no empty cell.
You think it is strange.
What happens with the cell? However, the cell is not empty. It has a data like character size is 0.

For instance, Suppose if you input the formula such as =if(A1="","",A1). If A1 cell is empty or has empty character string, the formula returns the empty character string like the length is 0. Again, we cannot see the data but there is text input.

Now, copy the cell and check the values by using paste special.
After that, the cell is transformed into values and it is stored as a empty character string as not seen.

So, if you want to make an empty cell, just use Del key.