To put it bluntly, Spain supports Italy's colonization efforts in Tunisia in exchange for Italy's support for Spain's colonization in Morocco.
As for colonization conflicts outside North Africa, such as Spain's colonial competition with France in West Africa, Italy does not need to adhere to this cooperation agreement.
This also provides flexibility for both governments. Although both Spain and Italy have competitive relationships with France in terms of colonization, currently Spain's colonies in Africa far exceed those of Italy.
While Italy is willing to cooperate with Spain, it is clear that Italy does not want to completely offend the French over Spain's West Africa colony.
The cooperation is limited to North Africa, ensuring that the gap in interests between Italy and Spain does not become too large. Although Morocco's land area is more extensive, Tunisia has more arable land, so it's roughly balanced.
