Welcome to the forum, Luminary Xion.

Yes, cells can be protected against the user changing them.

The Format Cell dialog has a Protection tab, one can set a cell to be Locked or not. The contents of a Locked cell cannot be changed. If a locked cell contains a formula, the value of that formula will change when the inputs change, but the cell will always contain the formula.

Locking of cells does not take effect unless the sheet is Protected.

Pre-2007, sheet protection is in the Tools menu.

I hope that helps.