An inner joins will only keep rows where the join condition is satisfied - all non matching rows from either table is dropped.
A left join will have the same rows as an inner join plus any other row from the table on the left side of the join but which does not satisfy the join condition. So, you will have some rows with null (empty) values for columns coming from the table on the right side of the join.
A right join is basically the opposite of a left join.
A full outer join will include all rows from both tables (even those that dont satisfy the join condition). So it is like a left join and a right join together.
You can see a practical example in QuickSight here Joining data - Amazon QuickSight
So, you just need to determine from which table you want to keep rows when the join condition is not satisfied and then choose the corresponding join condition. Additionally, you’d need to double check the join criteria to ensure that it makes sense for the tables you are joining.