How to connect one excel sheet to other excel sheet

Do you mean have the contents of a cell on one sheet appear in a cell on another sheet?

If so, it's easy if both sheets are part of the same workbook.

1. On the second sheet, highlight the cell you want the data to appear in, to link TO.
2. Enter an equal sign in that cell to start the formula, then use your mouse to switch to the first sheet and click on the cell that has the data in it already, the cell you want to link FROM.
3. Press ENTER.
4. Your cursor will return to the link TO cell and you will see that it now shows the data from the link FROM cell.

That's the simple explanation. Here's the formula explanation.

For one cell (A2) to show the contents of another cell (A1), the formula you enter cell A2 is =A1

That works if the cells are both on the same sheet. If they are on separate sheets, you simply have to add the name of the sheet and and exclamation point to the formula.

Sheet1, cell A1 is the data cell.
On Sheet2, in cell A2 enter the formula =Sheet1!A1

That's it.