Your perceived problem comes from thinking spreadsheet when in fact you
are using a relational database.

   You need to perform what is called normalization of the database.  It is
a design process.

   While this may not apply to you 100% hopefully this example will start
you thinking in the right direction.

   You have an inventory.  You may stock 100 different items,  You may have
0 or more of any individual item.  For example you may have

20 #45 computers
15 Model ERM hard drives
2000 USB cables.
etc.

   You would want a list of items and the number on hand.  That information
would be in one table

   You then may have a sale John Smith of:

2  #45 computers
1 Model ERM hard drives
3 USB cables.

   That would be another table listing what was sold on a specific sales
order

    Yet another table will list John Smith as well as his address telephone
number etc.

   All those tables hold information about one kind of thing (inventory,
sales, customers)

   Using queries, forms and reports you interact with all the tables.  For
example when you have a sale you put in John Smith (or customer #103) and
his name and address can appear taken from the customer table.  Next you
type in the Item # or name of the 2 computers and and information about the
computers is added including checking to make sure you have some.  You add
the number sold.

   In a report you can print out the sale listing everything sold to who
etc.  You can also make up a report showing the number of remaining
computers etc.  You don't store this information, it is computed anytime you
want it so additional sales and returns are recorded.

   The Northwind example database that ships with Access has some examples.

   That is why Access is called a relational database since the data is
related in different tables.