You can add ActieX control to create a form in the worksheet.
There is also the possibility to create a form outside the worksheet. See userForm. Worksheet are containers to hold ActiveX controls (as userForm are).
To use the forms controls in Excel, you must enable the Developer tab. See How to use the forms controls on a worksheet in Excel.
By pushing the Design Mode button, you set the forms object in an active mode or developer mode (ie it performs the code or it shows the properties)