Then in Dashboard it's Tables->Table value

How do you exactly display that table on a dashboard? 
I wrote a similar script, tested it, and it's working fine. It returns the table, as the above example.
I created a new DCI on the NetXMS server, with its origin being this script. When I go to the Last Values tab, the value of this DCI is show, e.g. Table@00000142F14623E0. 

On the script, I can use println associated with table->rows, row->values etc. to print the table,
but how do I display this table on the dashboard? I tried the Table Value element, but i didin't work.

Thank you in advance.

It worked!

object queries are for a bit different purpose. They are for selecting objects. Script in query is executed for each node and should return true or false. You can include additional fields into resulting table, but number of columns will be static.

One possible solution for your task is to create script table DCI on one of the nodes (could be NetXMS server itself) that will collect data from other nodes and populate the table. Then you can put content of that table on dashboard. You can choose "do not store" option for that table DCI to avoid keeping unnecessary information in database. Script for such DCI could be following:

result = new Table();
result->addColumn("sysName", DCI::STRING, "System Name", true);
result->addColumn("description", DCI::STRING, "Description", true);
result->addColumn("value", DCI::FLOAT, "Value");

for (node : GetAllNodes())
{
   for(dci : FindAllDCIs(node, null, "*latency*"))
   {
      value = GetDCIValue(node, dci->id);
      if (value != null)
      {
         row = result->addRow();
         result->set(row, 0, node->snmpSysName);
         result->set(row, 1, dci->description);
         result->set(row, 2, value);
      }
   }
}

return result;

Best regards,
Victor