An alias table breaks a loop by making a copy of a table that is referenced multiple times in the same query for different purposes. In such a situation, the referenced table is functioning as a lookup table on the data foundation.
The alias is identical to the base table, but with a different name. The data in the alias is exactly the same as the original table, but the different name tricks SQL into using the same database table for two different purposes.
In the Motors data foundation, the COUNTRY table has already been identified as a shared lookup table. It was identified because it is serving two purposes in the data foundation: providing data for the CLIENT table and the SHOWROOM table.
Another way of spotting the problem table in a loop is that it only has the one end of multiple one-to-many joins going into it. Check the other tables in the loop. If you find no others with only one-end joins, the loop can probably be resolved using an alias.