At the bottom of your Total Hours column, add a SUM formula: =SUM(E2:E31). This gives you a weekly or monthly total at a glance.
If you work across multiple projects, use a PivotTable. It sounds fancy, but it’s just Excel’s way of asking: “Want me to sort this mess for you?” Click Insert > PivotTable, drag “Project” into Rows and “Total Hours” into Values. Boom—you now know that “Emails” ate six hours of your life.