As you know in your lead scoring settings you set up the values/ranking for relative score and relative urgency
Marketo has an algorithm running in the background that takes those scores and gives the lead a ranking or priority this is now called 'engagement" in Salesforce.
In this case the engagement number of 110 is the new naming convention for "priority".
To understand how Relative Score Value and Urgency Score are calculated refer to:
Credit to: Veronica Holmes who kindly explained this to me.