Maybe I'll give you two simple and concrete examples.
A Canadian firm investing in Madagascar or vice versa would be interested to know what the withholding tax rate is on, say, dividends paid from a Madagascar subsidiary to the Canadian parent, or again, vice versa. The Canadian firm would want to have certainty as to the rate going forward over the term of the investment
As noted, this treaty would ensure that the maximum withholding dividend rate on income or dividends paid by a Madagascar subsidiary to a Canadian firm, as long as they have substantial investment in their Madagascar subsidiary, would not exceed 5%. That provides cost certainty in terms of their exposure to dividend withholding tax on their investment.
In Madagascar, another example would be where you have an entity, let's say a corporation or an individual, that could be considered under both the laws of Canada and the the law of Madagascar to be resident in both countries. The treaty provides more clear tie-breaker rules to help establish where that entity is resident. This can make a big difference in terms of the imposition of, say, income tax, which Canada imposes on their residents on their worldwide income.