"Many Tries" means that a student has attempted the same level at least 10 times and might need some assistance. You can click the name of the game to open it up in test drive and try it for yourself or work with the student from their screen to have them walk you through what they have tried, asking facilitating questions to help get the student unstuck.
How do you clear the alert?
Students have to complete the level to clear the alert.
How does a teacher see historical alerts for this year?
Go to the Standards tab and the Alerts sub-tab.
You'll be able to see the number of Many Tries alerts that the student received for all Objectives recommended or related to that standard.