There are a few ways you can recognize whether you have 1-phase or 3-phase connection.
First check the meter. Is there 220 / 230V here? Then it is a 1-phase group cabinet. Is there 3x220 / 230V or 380 / 400V here? Then it is a 3-phase connection.
Sometimes there is nothing on the meter. Then look at the wires that come out from underneath the connection. If there are two, you have a 1-phase group cabinet. If there are four, it is a 3-phase connection.
If you can’t see it despite these tips, contact your electricity provider. As the owner of the meter, they can tell you more about the connection.