Hi @JuanCifu,
This is an issue we at Meraki are currently working towards addressing -- we know that the "Aggregate-X" labelling can be confusing right now when looking at the MAC forwarding table.
Unfortunately, this also means that there isn't a very good way to identify which switchports "Aggregate-X" maps to using just Dashboard right now.
If the other side of the link agg goes to a device that sends CDP or LLDP data, you can go to "Switch" -> "Switch ports", select the "CDP/LLDP" column to be displayed using the spanner icon in the top-right hand corner of the table, and then filter for the MAC address you see in the MAC forwarding table by copying and pasting the MAC address into the search bar at the top of the table in the Switch ports page.
You'll then see the ports the "Aggregate-X" group maps to.
Otherwise, feel free to open a case with our Support team, and they'll be able to help you map the "Aggregate-X" group to particular ports!