One of the newest features in Microsoft Teams is Excel Live, which gives you the opportunity to collaborate on an Excel spreadsheet when you are presenting it in a Teams meeting. Here’s how it works…
When you go to share content in a Teams meeting, you will see a new section for Excel Live where you can select a spreadsheet to share in the meeting:

Once you select a spreadsheet, Teams lets you know this spreadsheet will be shared with everyone in the meeting:

At that point, everyone in the meeting can start updating the spreadsheet, and you’ll see the initials of individuals and where they are on the screen:

Some thoughts… this is a new feature, so there will likely be some “growing pains” as it gets used more frequently. When we tested during a session, we found out very quickly that Excel Live currently only supports up to 25 people in a meeting. After those 25 people join, others get a message saying they do not have access. Also, much like doing collaborative editing in Excel, two people cannot be updating the same element at the same time. You may see messages saying that your change wasn’t allowed as someone else already edited that area.