A lookup field allows you to look up a specific field in a linked record.
For example, if you have an Orders table with a field linking to Clients, you could create a lookup field that displays the linked client's address.
Lookup configuration is pretty straightforward. First, you pick the field with the linked records you want to look up. Then, you pick the cell on those linked records that you want to display.
Note that if there are multiple linked records, the lookup will concatenate the cell values and separate them with a comma.