If you have the fine grain priority setting turned on from Admin, then activity with the highest number takes precedence. So, if multiple activities are assigned to the same location with the same audience, the activity with 999 takes precedence over the one set to 0.
If you don't have fine grain set, you will see low, medium or high. Low priority will essentially be 0 and occur after high.
https://experienceleague.adobe.com/en/docs/target/using/activities/activity-settings