I understood that the asker has two columns and wants to find how many rows have matching entries, between those columns. If column A contains, say, potato, turnip, and carrot, and column B contains potato, broccoli, and carrot, then you'd want the value 2.

The normal thing to do in this situation is to create a third column that has a comparison formula on every row, and then count the matches. You first enter =IF(A1=B1;1;0) into C1. Then you select the cells you need in column C and use Edit > Fill > Down. This copies the formula and changes it to suit every row. Then you put something like =SUM(C1:C100) somewhere to count how many rows match. You can hide the third column if you think it looks messy.

Another way to do this, without the extra column, would be to write a macro function. Depending on how versatile you'd want the function to be, it could be quite short or tens of lines long.